Merge pull request #6143 from robintown/hide-events-perf

src/TextForEvent.ts

@@ -21,153 +21,161 @@ import SettingsStore from "./settings/SettingsStore";
 import {ALL_RULE_TYPES, ROOM_RULE_TYPES, SERVER_RULE_TYPES, USER_RULE_TYPES} from "./mjolnir/BanList";
 import {WIDGET_LAYOUT_EVENT_TYPE} from "./stores/widgets/WidgetLayoutStore";
 
-function textForMemberEvent(ev) {
+// These functions are frequently used just to check whether an event has
+// any text to display at all. For this reason they return deferred values
+// to avoid the expense of looking up translations when they're not needed.
+
+function textForMemberEvent(ev): () => string | null {
     // XXX: SYJS-16 "sender is sometimes null for join messages"
     const senderName = ev.sender ? ev.sender.name : ev.getSender();
     const targetName = ev.target ? ev.target.name : ev.getStateKey();
     const prevContent = ev.getPrevContent();
     const content = ev.getContent();
 
-    const reason = content.reason ? (_t('Reason') + ': ' + content.reason) : '';
+    const getReason = () => content.reason ? (_t('Reason') + ': ' + content.reason) : '';
     switch (content.membership) {
         case 'invite': {
             const threePidContent = content.third_party_invite;
             if (threePidContent) {
                 if (threePidContent.display_name) {
-                    return _t('%(targetName)s accepted the invitation for %(displayName)s.', {
+                    return () => _t('%(targetName)s accepted the invitation for %(displayName)s.', {
                         targetName,
                         displayName: threePidContent.display_name,
                     });
                 } else {
-                    return _t('%(targetName)s accepted an invitation.', {targetName});
+                    return () => _t('%(targetName)s accepted an invitation.', {targetName});
                 }
             } else {
-                return _t('%(senderName)s invited %(targetName)s.', {senderName, targetName});
+                return () => _t('%(senderName)s invited %(targetName)s.', {senderName, targetName});
             }
         }
         case 'ban':
-            return _t('%(senderName)s banned %(targetName)s.', {senderName, targetName}) + ' ' + reason;
+            return () => _t('%(senderName)s banned %(targetName)s.', {senderName, targetName}) + ' ' + getReason();
         case 'join':
             if (prevContent && prevContent.membership === 'join') {
                 if (prevContent.displayname && content.displayname && prevContent.displayname !== content.displayname) {
-                    return _t('%(oldDisplayName)s changed their display name to %(displayName)s.', {
+                    return () => _t('%(oldDisplayName)s changed their display name to %(displayName)s.', {
                         oldDisplayName: prevContent.displayname,
                         displayName: content.displayname,
                     });
                 } else if (!prevContent.displayname && content.displayname) {
-                    return _t('%(senderName)s set their display name to %(displayName)s.', {
+                    return () => _t('%(senderName)s set their display name to %(displayName)s.', {
                         senderName: ev.getSender(),
                         displayName: content.displayname,
                     });
                 } else if (prevContent.displayname && !content.displayname) {
-                    return _t('%(senderName)s removed their display name (%(oldDisplayName)s).', {
+                    return () => _t('%(senderName)s removed their display name (%(oldDisplayName)s).', {
                         senderName,
                         oldDisplayName: prevContent.displayname,
                     });
                 } else if (prevContent.avatar_url && !content.avatar_url) {
-                    return _t('%(senderName)s removed their profile picture.', {senderName});
+                    return () => _t('%(senderName)s removed their profile picture.', {senderName});
                 } else if (prevContent.avatar_url && content.avatar_url &&
                     prevContent.avatar_url !== content.avatar_url) {
-                    return _t('%(senderName)s changed their profile picture.', {senderName});
+                    return () => _t('%(senderName)s changed their profile picture.', {senderName});
                 } else if (!prevContent.avatar_url && content.avatar_url) {
-                    return _t('%(senderName)s set a profile picture.', {senderName});
+                    return () => _t('%(senderName)s set a profile picture.', {senderName});
                 } else if (SettingsStore.getValue("showHiddenEventsInTimeline")) {
                     // This is a null rejoin, it will only be visible if the Labs option is enabled
-                    return _t("%(senderName)s made no change.", {senderName});
+                    return () => _t("%(senderName)s made no change.", {senderName});
                 } else {
-                    return "";
+                    return null;
                 }
             } else {
                 if (!ev.target) console.warn("Join message has no target! -- " + ev.getContent().state_key);
-                return _t('%(targetName)s joined the room.', {targetName});
+                return () => _t('%(targetName)s joined the room.', {targetName});
             }
         case 'leave':
             if (ev.getSender() === ev.getStateKey()) {
                 if (prevContent.membership === "invite") {
-                    return _t('%(targetName)s rejected the invitation.', {targetName});
+                    return () => _t('%(targetName)s rejected the invitation.', {targetName});
                 } else {
-                    return _t('%(targetName)s left the room.', {targetName});
+                    return () => _t('%(targetName)s left the room.', {targetName});
                 }
             } else if (prevContent.membership === "ban") {
-                return _t('%(senderName)s unbanned %(targetName)s.', {senderName, targetName});
+                return () => _t('%(senderName)s unbanned %(targetName)s.', {senderName, targetName});
             } else if (prevContent.membership === "invite") {
-                return _t('%(senderName)s withdrew %(targetName)s\'s invitation.', {
+                return () => _t('%(senderName)s withdrew %(targetName)s\'s invitation.', {
                     senderName,
                     targetName,
-                }) + ' ' + reason;
+                }) + ' ' + getReason();
             } else if (prevContent.membership === "join") {
-                return _t('%(senderName)s kicked %(targetName)s.', {senderName, targetName}) + ' ' + reason;
+                return () => _t('%(senderName)s kicked %(targetName)s.', {senderName, targetName}) + ' ' + getReason();
             } else {
-                return "";
+                return null;
             }
     }
 }
 
-function textForTopicEvent(ev) {
+function textForTopicEvent(ev): () => string | null {
     const senderDisplayName = ev.sender && ev.sender.name ? ev.sender.name : ev.getSender();
-    return _t('%(senderDisplayName)s changed the topic to "%(topic)s".', {
+    return () => _t('%(senderDisplayName)s changed the topic to "%(topic)s".', {
         senderDisplayName,
         topic: ev.getContent().topic,
     });
 }
 
-function textForRoomNameEvent(ev) {
+function textForRoomNameEvent(ev): () => string | null {
     const senderDisplayName = ev.sender && ev.sender.name ? ev.sender.name : ev.getSender();
 
     if (!ev.getContent().name || ev.getContent().name.trim().length === 0) {
-        return _t('%(senderDisplayName)s removed the room name.', {senderDisplayName});
+        return () => _t('%(senderDisplayName)s removed the room name.', {senderDisplayName});
     }
     if (ev.getPrevContent().name) {
-        return _t('%(senderDisplayName)s changed the room name from %(oldRoomName)s to %(newRoomName)s.', {
+        return () => _t('%(senderDisplayName)s changed the room name from %(oldRoomName)s to %(newRoomName)s.', {
             senderDisplayName,
             oldRoomName: ev.getPrevContent().name,
             newRoomName: ev.getContent().name,
         });
     }
-    return _t('%(senderDisplayName)s changed the room name to %(roomName)s.', {
+    return () => _t('%(senderDisplayName)s changed the room name to %(roomName)s.', {
         senderDisplayName,
         roomName: ev.getContent().name,
     });
 }
 
-function textForTombstoneEvent(ev) {
+function textForTombstoneEvent(ev): () => string | null {
     const senderDisplayName = ev.sender && ev.sender.name ? ev.sender.name : ev.getSender();
-    return _t('%(senderDisplayName)s upgraded this room.', {senderDisplayName});
+    return () => _t('%(senderDisplayName)s upgraded this room.', {senderDisplayName});
 }
 
-function textForJoinRulesEvent(ev) {
+function textForJoinRulesEvent(ev): () => string | null {
     const senderDisplayName = ev.sender && ev.sender.name ? ev.sender.name : ev.getSender();
     switch (ev.getContent().join_rule) {
         case "public":
-            return _t('%(senderDisplayName)s made the room public to whoever knows the link.', {senderDisplayName});
+            return () => _t('%(senderDisplayName)s made the room public to whoever knows the link.', {
+                senderDisplayName,
+            });
         case "invite":
-            return _t('%(senderDisplayName)s made the room invite only.', {senderDisplayName});
+            return () => _t('%(senderDisplayName)s made the room invite only.', {
+                senderDisplayName,
+            });
         default:
             // The spec supports "knock" and "private", however nothing implements these.
-            return _t('%(senderDisplayName)s changed the join rule to %(rule)s', {
+            return () => _t('%(senderDisplayName)s changed the join rule to %(rule)s', {
                 senderDisplayName,
                 rule: ev.getContent().join_rule,
             });
     }
 }
 
-function textForGuestAccessEvent(ev) {
+function textForGuestAccessEvent(ev): () => string | null {
     const senderDisplayName = ev.sender && ev.sender.name ? ev.sender.name : ev.getSender();
     switch (ev.getContent().guest_access) {
         case "can_join":
-            return _t('%(senderDisplayName)s has allowed guests to join the room.', {senderDisplayName});
+            return () => _t('%(senderDisplayName)s has allowed guests to join the room.', {senderDisplayName});
         case "forbidden":
-            return _t('%(senderDisplayName)s has prevented guests from joining the room.', {senderDisplayName});
+            return () => _t('%(senderDisplayName)s has prevented guests from joining the room.', {senderDisplayName});
         default:
             // There's no other options we can expect, however just for safety's sake we'll do this.
-            return _t('%(senderDisplayName)s changed guest access to %(rule)s', {
+            return () => _t('%(senderDisplayName)s changed guest access to %(rule)s', {
                 senderDisplayName,
                 rule: ev.getContent().guest_access,
             });
     }
 }
 
-function textForRelatedGroupsEvent(ev) {
+function textForRelatedGroupsEvent(ev): () => string | null {
     const senderDisplayName = ev.sender && ev.sender.name ? ev.sender.name : ev.getSender();
     const groups = ev.getContent().groups || [];
     const prevGroups = ev.getPrevContent().groups || [];
@@ -175,17 +183,17 @@ function textForRelatedGroupsEvent(ev) {
     const removed = prevGroups.filter((g) => !groups.includes(g));
 
     if (added.length && !removed.length) {
-        return _t('%(senderDisplayName)s enabled flair for %(groups)s in this room.', {
+        return () => _t('%(senderDisplayName)s enabled flair for %(groups)s in this room.', {
             senderDisplayName,
             groups: added.join(', '),
         });
     } else if (!added.length && removed.length) {
-        return _t('%(senderDisplayName)s disabled flair for %(groups)s in this room.', {
+        return () => _t('%(senderDisplayName)s disabled flair for %(groups)s in this room.', {
             senderDisplayName,
             groups: removed.join(', '),
         });
     } else if (added.length && removed.length) {
-        return _t('%(senderDisplayName)s enabled flair for %(newGroups)s and disabled flair for ' +
+        return () => _t('%(senderDisplayName)s enabled flair for %(newGroups)s and disabled flair for ' +
             '%(oldGroups)s in this room.', {
             senderDisplayName,
             newGroups: added.join(', '),
@@ -193,11 +201,11 @@ function textForRelatedGroupsEvent(ev) {
         });
     } else {
         // Don't bother rendering this change (because there were no changes)
-        return '';
+        return null;
     }
 }
 
-function textForServerACLEvent(ev) {
+function textForServerACLEvent(ev): () => string | null {
     const senderDisplayName = ev.sender && ev.sender.name ? ev.sender.name : ev.getSender();
     const prevContent = ev.getPrevContent();
     const current = ev.getContent();
@@ -207,11 +215,11 @@ function textForServerACLEvent(ev) {
         allow_ip_literals: !(prevContent.allow_ip_literals === false),
     };
 
-    let text = "";
+    let getText = null;
     if (prev.deny.length === 0 && prev.allow.length === 0) {
-        text = _t("%(senderDisplayName)s set the server ACLs for this room.", {senderDisplayName});
+        getText = () => _t("%(senderDisplayName)s set the server ACLs for this room.", {senderDisplayName});
     } else {
-        text = _t("%(senderDisplayName)s changed the server ACLs for this room.", {senderDisplayName});
+        getText = () => _t("%(senderDisplayName)s changed the server ACLs for this room.", {senderDisplayName});
     }
 
     if (!Array.isArray(current.allow)) {
@@ -220,24 +228,27 @@ function textForServerACLEvent(ev) {
 
     // If we know for sure everyone is banned, mark the room as obliterated
     if (current.allow.length === 0) {
-        return text + " " + _t("🎉 All servers are banned from participating! This room can no longer be used.");
+        return () => getText() + " " +
+            _t("🎉 All servers are banned from participating! This room can no longer be used.");
     }
 
-    return text;
+    return getText;
 }
 
-function textForMessageEvent(ev) {
+function textForMessageEvent(ev): () => string | null {
-    const senderDisplayName = ev.sender && ev.sender.name ? ev.sender.name : ev.getSender();
+    return () => {
-    let message = senderDisplayName + ': ' + ev.getContent().body;
+        const senderDisplayName = ev.sender && ev.sender.name ? ev.sender.name : ev.getSender();
-    if (ev.getContent().msgtype === "m.emote") {
+        let message = senderDisplayName + ': ' + ev.getContent().body;
-        message = "* " + senderDisplayName + " " + message;
+        if (ev.getContent().msgtype === "m.emote") {
-    } else if (ev.getContent().msgtype === "m.image") {
+            message = "* " + senderDisplayName + " " + message;
-        message = _t('%(senderDisplayName)s sent an image.', {senderDisplayName});
+        } else if (ev.getContent().msgtype === "m.image") {
-    }
+            message = _t('%(senderDisplayName)s sent an image.', {senderDisplayName});
-    return message;
+        }
+        return message;
+    };
 }
 
-function textForCanonicalAliasEvent(ev) {
+function textForCanonicalAliasEvent(ev): () => string | null {
     const senderName = ev.sender && ev.sender.name ? ev.sender.name : ev.getSender();
     const oldAlias = ev.getPrevContent().alias;
     const oldAltAliases = ev.getPrevContent().alt_aliases || [];
@@ -248,96 +259,100 @@ function textForCanonicalAliasEvent(ev) {
 
     if (!removedAltAliases.length && !addedAltAliases.length) {
         if (newAlias) {
-            return _t('%(senderName)s set the main address for this room to %(address)s.', {
+            return () => _t('%(senderName)s set the main address for this room to %(address)s.', {
                 senderName: senderName,
                 address: ev.getContent().alias,
             });
         } else if (oldAlias) {
-            return _t('%(senderName)s removed the main address for this room.', {
+            return () => _t('%(senderName)s removed the main address for this room.', {
                 senderName: senderName,
             });
         }
     } else if (newAlias === oldAlias) {
         if (addedAltAliases.length && !removedAltAliases.length) {
-            return _t('%(senderName)s added the alternative addresses %(addresses)s for this room.', {
+            return () => _t('%(senderName)s added the alternative addresses %(addresses)s for this room.', {
                 senderName: senderName,
                 addresses: addedAltAliases.join(", "),
                 count: addedAltAliases.length,
             });
         } if (removedAltAliases.length && !addedAltAliases.length) {
-            return _t('%(senderName)s removed the alternative addresses %(addresses)s for this room.', {
+            return () => _t('%(senderName)s removed the alternative addresses %(addresses)s for this room.', {
                 senderName: senderName,
                 addresses: removedAltAliases.join(", "),
                 count: removedAltAliases.length,
             });
         } if (removedAltAliases.length && addedAltAliases.length) {
-            return _t('%(senderName)s changed the alternative addresses for this room.', {
+            return () => _t('%(senderName)s changed the alternative addresses for this room.', {
                 senderName: senderName,
             });
         }
     } else {
         // both alias and alt_aliases where modified
-        return _t('%(senderName)s changed the main and alternative addresses for this room.', {
+        return () => _t('%(senderName)s changed the main and alternative addresses for this room.', {
             senderName: senderName,
         });
     }
     // in case there is no difference between the two events,
     // say something as we can't simply hide the tile from here
-    return _t('%(senderName)s changed the addresses for this room.', {
+    return () => _t('%(senderName)s changed the addresses for this room.', {
         senderName: senderName,
     });
 }
 
-function textForCallAnswerEvent(event) {
+function textForCallAnswerEvent(event): () => string | null {
-    const senderName = event.sender ? event.sender.name : _t('Someone');
+    return () => {
-    const supported = MatrixClientPeg.get().supportsVoip() ? '' : _t('(not supported by this browser)');
+        const senderName = event.sender ? event.sender.name : _t('Someone');
-    return _t('%(senderName)s answered the call.', {senderName}) + ' ' + supported;
+        const supported = MatrixClientPeg.get().supportsVoip() ? '' : _t('(not supported by this browser)');
+        return _t('%(senderName)s answered the call.', {senderName}) + ' ' + supported;
+    };
 }
 
-function textForCallHangupEvent(event) {
+function textForCallHangupEvent(event): () => string | null {
-    const senderName = event.sender ? event.sender.name : _t('Someone');
+    const getSenderName = () => event.sender ? event.sender.name : _t('Someone');
     const eventContent = event.getContent();
-    let reason = "";
+    let getReason = () => "";
     if (!MatrixClientPeg.get().supportsVoip()) {
-        reason = _t('(not supported by this browser)');
+        getReason = () => _t('(not supported by this browser)');
     } else if (eventContent.reason) {
         if (eventContent.reason === "ice_failed") {
             // We couldn't establish a connection at all
-            reason = _t('(could not connect media)');
+            getReason = () => _t('(could not connect media)');
         } else if (eventContent.reason === "ice_timeout") {
             // We established a connection but it died
-            reason = _t('(connection failed)');
+            getReason = () => _t('(connection failed)');
         } else if (eventContent.reason === "user_media_failed") {
             // The other side couldn't open capture devices
-            reason = _t("(their device couldn't start the camera / microphone)");
+            getReason = () => _t("(their device couldn't start the camera / microphone)");
         } else if (eventContent.reason === "unknown_error") {
             // An error code the other side doesn't have a way to express
             // (as opposed to an error code they gave but we don't know about,
             // in which case we show the error code)
-            reason = _t("(an error occurred)");
+            getReason = () => _t("(an error occurred)");
         } else if (eventContent.reason === "invite_timeout") {
-            reason = _t('(no answer)');
+            getReason = () => _t('(no answer)');
         } else if (eventContent.reason === "user hangup" || eventContent.reason === "user_hangup") {
             // workaround for https://github.com/vector-im/element-web/issues/5178
             // it seems Android randomly sets a reason of "user hangup" which is
             // interpreted as an error code :(
             // https://github.com/vector-im/riot-android/issues/2623
             // Also the correct hangup code as of VoIP v1 (with underscore)
-            reason = '';
+            getReason = () => '';
         } else {
-            reason = _t('(unknown failure: %(reason)s)', {reason: eventContent.reason});
+            getReason = () => _t('(unknown failure: %(reason)s)', {reason: eventContent.reason});
         }
     }
-    return _t('%(senderName)s ended the call.', {senderName}) + ' ' + reason;
+    return () => _t('%(senderName)s ended the call.', {senderName: getSenderName()}) + ' ' + getReason();
 }
 
-function textForCallRejectEvent(event) {
+function textForCallRejectEvent(event): () => string | null {
-    const senderName = event.sender ? event.sender.name : _t('Someone');
+    return () => {
-    return _t('%(senderName)s declined the call.', {senderName});
+        const senderName = event.sender ? event.sender.name : _t('Someone');
+        return _t('%(senderName)s declined the call.', {senderName});
+    };
 }
 
-function textForCallInviteEvent(event) {
+function textForCallInviteEvent(event): () => string | null {
-    const senderName = event.sender ? event.sender.name : _t('Someone');
+    const getSenderName = () => event.sender ? event.sender.name : _t('Someone');
     // FIXME: Find a better way to determine this from the event?
     let isVoice = true;
     if (event.getContent().offer && event.getContent().offer.sdp &&
@@ -350,48 +365,55 @@ function textForCallInviteEvent(event) {
     // can have a hard time translating those strings. In an effort to make translations easier
     // and more accurate, we break out the string-based variables to a couple booleans.
     if (isVoice && isSupported) {
-        return _t("%(senderName)s placed a voice call.", {senderName});
+        return () => _t("%(senderName)s placed a voice call.", {
+            senderName: getSenderName(),
+        });
     } else if (isVoice && !isSupported) {
-        return _t("%(senderName)s placed a voice call. (not supported by this browser)", {senderName});
+        return () => _t("%(senderName)s placed a voice call. (not supported by this browser)", {
+            senderName: getSenderName(),
+        });
     } else if (!isVoice && isSupported) {
-        return _t("%(senderName)s placed a video call.", {senderName});
+        return () => _t("%(senderName)s placed a video call.", {
+            senderName: getSenderName(),
+        });
     } else if (!isVoice && !isSupported) {
-        return _t("%(senderName)s placed a video call. (not supported by this browser)", {senderName});
+        return () => _t("%(senderName)s placed a video call. (not supported by this browser)", {
+            senderName: getSenderName(),
+        });
     }
 }
 
-function textForThreePidInviteEvent(event) {
+function textForThreePidInviteEvent(event): () => string | null {
     const senderName = event.sender ? event.sender.name : event.getSender();
 
     if (!isValid3pidInvite(event)) {
-        const targetDisplayName = event.getPrevContent().display_name || _t("Someone");
+        return () => _t('%(senderName)s revoked the invitation for %(targetDisplayName)s to join the room.', {
-        return _t('%(senderName)s revoked the invitation for %(targetDisplayName)s to join the room.', {
             senderName,
-            targetDisplayName,
+            targetDisplayName: event.getPrevContent().display_name || _t("Someone"),
         });
     }
 
-    return _t('%(senderName)s sent an invitation to %(targetDisplayName)s to join the room.', {
+    return () => _t('%(senderName)s sent an invitation to %(targetDisplayName)s to join the room.', {
         senderName,
         targetDisplayName: event.getContent().display_name,
     });
 }
 
-function textForHistoryVisibilityEvent(event) {
+function textForHistoryVisibilityEvent(event): () => string | null {
     const senderName = event.sender ? event.sender.name : event.getSender();
     switch (event.getContent().history_visibility) {
         case 'invited':
-            return _t('%(senderName)s made future room history visible to all room members, '
+            return () => _t('%(senderName)s made future room history visible to all room members, '
                 + 'from the point they are invited.', {senderName});
         case 'joined':
-            return _t('%(senderName)s made future room history visible to all room members, '
+            return () => _t('%(senderName)s made future room history visible to all room members, '
                 + 'from the point they joined.', {senderName});
         case 'shared':
-            return _t('%(senderName)s made future room history visible to all room members.', {senderName});
+            return () => _t('%(senderName)s made future room history visible to all room members.', {senderName});
         case 'world_readable':
-            return _t('%(senderName)s made future room history visible to anyone.', {senderName});
+            return () => _t('%(senderName)s made future room history visible to anyone.', {senderName});
         default:
-            return _t('%(senderName)s made future room history visible to unknown (%(visibility)s).', {
+            return () => _t('%(senderName)s made future room history visible to unknown (%(visibility)s).', {
                 senderName,
                 visibility: event.getContent().history_visibility,
             });
@@ -399,11 +421,11 @@ function textForHistoryVisibilityEvent(event) {
 }
 
 // Currently will only display a change if a user's power level is changed
-function textForPowerEvent(event) {
+function textForPowerEvent(event): () => string | null {
     const senderName = event.sender ? event.sender.name : event.getSender();
     if (!event.getPrevContent() || !event.getPrevContent().users ||
         !event.getContent() || !event.getContent().users) {
-        return '';
+        return null;
     }
     const userDefault = event.getContent().users_default || 0;
     // Construct set of userIds
@@ -418,38 +440,38 @@ function textForPowerEvent(event) {
             if (users.indexOf(userId) === -1) users.push(userId);
         },
     );
-    const diff = [];
+    const diffs = [];
-    // XXX: This is also surely broken for i18n
     users.forEach((userId) => {
         // Previous power level
         const from = event.getPrevContent().users[userId];
         // Current power level
         const to = event.getContent().users[userId];
         if (to !== from) {
-            diff.push(
+            diffs.push({ userId, from, to });
-                _t('%(userId)s from %(fromPowerLevel)s to %(toPowerLevel)s', {
-                    userId,
-                    fromPowerLevel: Roles.textualPowerLevel(from, userDefault),
-                    toPowerLevel: Roles.textualPowerLevel(to, userDefault),
-                }),
-            );
         }
     });
-    if (!diff.length) {
+    if (!diffs.length) {
-        return '';
+        return null;
     }
-    return _t('%(senderName)s changed the power level of %(powerLevelDiffText)s.', {
+    // XXX: This is also surely broken for i18n
+    return () => _t('%(senderName)s changed the power level of %(powerLevelDiffText)s.', {
         senderName,
-        powerLevelDiffText: diff.join(", "),
+        powerLevelDiffText: diffs.map(diff =>
+            _t('%(userId)s from %(fromPowerLevel)s to %(toPowerLevel)s', {
+                userId: diff.userId,
+                fromPowerLevel: Roles.textualPowerLevel(diff.from, userDefault),
+                toPowerLevel: Roles.textualPowerLevel(diff.to, userDefault),
+            }),
+        ).join(", "),
     });
 }
 
-function textForPinnedEvent(event) {
+function textForPinnedEvent(event): () => string | null {
     const senderName = event.sender ? event.sender.name : event.getSender();
-    return _t("%(senderName)s changed the pinned messages for the room.", {senderName});
+    return () => _t("%(senderName)s changed the pinned messages for the room.", {senderName});
 }
 
-function textForWidgetEvent(event) {
+function textForWidgetEvent(event): () => string | null {
     const senderName = event.getSender();
     const {name: prevName, type: prevType, url: prevUrl} = event.getPrevContent();
     const {name, type, url} = event.getContent() || {};
@@ -464,27 +486,27 @@ function textForWidgetEvent(event) {
     // equivalent to that condition.
     if (url) {
         if (prevUrl) {
-            return _t('%(widgetName)s widget modified by %(senderName)s', {
+            return () => _t('%(widgetName)s widget modified by %(senderName)s', {
                 widgetName, senderName,
             });
         } else {
-            return _t('%(widgetName)s widget added by %(senderName)s', {
+            return () => _t('%(widgetName)s widget added by %(senderName)s', {
                 widgetName, senderName,
             });
         }
     } else {
-        return _t('%(widgetName)s widget removed by %(senderName)s', {
+        return () => _t('%(widgetName)s widget removed by %(senderName)s', {
             widgetName, senderName,
         });
     }
 }
 
-function textForWidgetLayoutEvent(event) {
+function textForWidgetLayoutEvent(event): () => string | null {
     const senderName = event.sender?.name || event.getSender();
-    return _t("%(senderName)s has updated the widget layout", {senderName});
+    return () => _t("%(senderName)s has updated the widget layout", {senderName});
 }
 
-function textForMjolnirEvent(event) {
+function textForMjolnirEvent(event): () => string | null {
     const senderName = event.getSender();
     const {entity: prevEntity} = event.getPrevContent();
     const {entity, recommendation, reason} = event.getContent();
@@ -492,74 +514,74 @@ function textForMjolnirEvent(event) {
     // Rule removed
     if (!entity) {
         if (USER_RULE_TYPES.includes(event.getType())) {
-            return _t("%(senderName)s removed the rule banning users matching %(glob)s",
+            return () => _t("%(senderName)s removed the rule banning users matching %(glob)s",
                 {senderName, glob: prevEntity});
         } else if (ROOM_RULE_TYPES.includes(event.getType())) {
-            return _t("%(senderName)s removed the rule banning rooms matching %(glob)s",
+            return () => _t("%(senderName)s removed the rule banning rooms matching %(glob)s",
                 {senderName, glob: prevEntity});
         } else if (SERVER_RULE_TYPES.includes(event.getType())) {
-            return _t("%(senderName)s removed the rule banning servers matching %(glob)s",
+            return () => _t("%(senderName)s removed the rule banning servers matching %(glob)s",
                 {senderName, glob: prevEntity});
         }
 
         // Unknown type. We'll say something, but we shouldn't end up here.
-        return _t("%(senderName)s removed a ban rule matching %(glob)s", {senderName, glob: prevEntity});
+        return () => _t("%(senderName)s removed a ban rule matching %(glob)s", {senderName, glob: prevEntity});
     }
 
     // Invalid rule
-    if (!recommendation || !reason) return _t(`%(senderName)s updated an invalid ban rule`, {senderName});
+    if (!recommendation || !reason) return () => _t(`%(senderName)s updated an invalid ban rule`, {senderName});
 
     // Rule updated
     if (entity === prevEntity) {
         if (USER_RULE_TYPES.includes(event.getType())) {
-            return _t("%(senderName)s updated the rule banning users matching %(glob)s for %(reason)s",
+            return () => _t("%(senderName)s updated the rule banning users matching %(glob)s for %(reason)s",
                 {senderName, glob: entity, reason});
         } else if (ROOM_RULE_TYPES.includes(event.getType())) {
-            return _t("%(senderName)s updated the rule banning rooms matching %(glob)s for %(reason)s",
+            return () => _t("%(senderName)s updated the rule banning rooms matching %(glob)s for %(reason)s",
                 {senderName, glob: entity, reason});
         } else if (SERVER_RULE_TYPES.includes(event.getType())) {
-            return _t("%(senderName)s updated the rule banning servers matching %(glob)s for %(reason)s",
+            return () => _t("%(senderName)s updated the rule banning servers matching %(glob)s for %(reason)s",
                 {senderName, glob: entity, reason});
         }
 
         // Unknown type. We'll say something but we shouldn't end up here.
-        return _t("%(senderName)s updated a ban rule matching %(glob)s for %(reason)s",
+        return () => _t("%(senderName)s updated a ban rule matching %(glob)s for %(reason)s",
             {senderName, glob: entity, reason});
     }
 
     // New rule
     if (!prevEntity) {
         if (USER_RULE_TYPES.includes(event.getType())) {
-            return _t("%(senderName)s created a rule banning users matching %(glob)s for %(reason)s",
+            return () => _t("%(senderName)s created a rule banning users matching %(glob)s for %(reason)s",
                 {senderName, glob: entity, reason});
         } else if (ROOM_RULE_TYPES.includes(event.getType())) {
-            return _t("%(senderName)s created a rule banning rooms matching %(glob)s for %(reason)s",
+            return () => _t("%(senderName)s created a rule banning rooms matching %(glob)s for %(reason)s",
                 {senderName, glob: entity, reason});
         } else if (SERVER_RULE_TYPES.includes(event.getType())) {
-            return _t("%(senderName)s created a rule banning servers matching %(glob)s for %(reason)s",
+            return () => _t("%(senderName)s created a rule banning servers matching %(glob)s for %(reason)s",
                 {senderName, glob: entity, reason});
         }
 
         // Unknown type. We'll say something but we shouldn't end up here.
-        return _t("%(senderName)s created a ban rule matching %(glob)s for %(reason)s",
+        return () => _t("%(senderName)s created a ban rule matching %(glob)s for %(reason)s",
             {senderName, glob: entity, reason});
     }
 
     // else the entity !== prevEntity - count as a removal & add
     if (USER_RULE_TYPES.includes(event.getType())) {
-        return _t(
+        return () => _t(
             "%(senderName)s changed a rule that was banning users matching %(oldGlob)s to matching " +
             "%(newGlob)s for %(reason)s",
             {senderName, oldGlob: prevEntity, newGlob: entity, reason},
         );
     } else if (ROOM_RULE_TYPES.includes(event.getType())) {
-        return _t(
+        return () => _t(
             "%(senderName)s changed a rule that was banning rooms matching %(oldGlob)s to matching " +
             "%(newGlob)s for %(reason)s",
             {senderName, oldGlob: prevEntity, newGlob: entity, reason},
         );
     } else if (SERVER_RULE_TYPES.includes(event.getType())) {
-        return _t(
+        return () => _t(
             "%(senderName)s changed a rule that was banning servers matching %(oldGlob)s to matching " +
             "%(newGlob)s for %(reason)s",
             {senderName, oldGlob: prevEntity, newGlob: entity, reason},
@@ -567,11 +589,15 @@ function textForMjolnirEvent(event) {
     }
 
     // Unknown type. We'll say something but we shouldn't end up here.
-    return _t("%(senderName)s updated a ban rule that was matching %(oldGlob)s to matching %(newGlob)s " +
+    return () => _t("%(senderName)s updated a ban rule that was matching %(oldGlob)s to matching %(newGlob)s " +
         "for %(reason)s", {senderName, oldGlob: prevEntity, newGlob: entity, reason});
 }
 
-const handlers = {
+interface IHandlers {
+    [type: string]: (ev: any) => (() => string | null);
+}
+
+const handlers: IHandlers = {
     'm.room.message': textForMessageEvent,
     'm.call.invite': textForCallInviteEvent,
     'm.call.answer': textForCallAnswerEvent,
@@ -579,7 +605,7 @@ const handlers = {
     'm.call.reject': textForCallRejectEvent,
 };
 
-const stateHandlers = {
+const stateHandlers: IHandlers = {
     'm.room.canonical_alias': textForCanonicalAliasEvent,
     'm.room.name': textForRoomNameEvent,
     'm.room.topic': textForTopicEvent,
@@ -604,8 +630,12 @@ for (const evType of ALL_RULE_TYPES) {
     stateHandlers[evType] = textForMjolnirEvent;
 }
 
-export function textForEvent(ev) {
+export function hasText(ev): boolean {
     const handler = (ev.isState() ? stateHandlers : handlers)[ev.getType()];
-    if (handler) return handler(ev);
+    return Boolean(handler?.(ev));
-    return '';
+}
+
+export function textForEvent(ev): string {
+    const handler = (ev.isState() ? stateHandlers : handlers)[ev.getType()];
+    return handler?.(ev)?.() || '';
 }

src/components/structures/MessagePanel.js

@@ -25,10 +25,11 @@ import * as sdk from '../../index';
 
 import {MatrixClientPeg} from '../../MatrixClientPeg';
 import SettingsStore from '../../settings/SettingsStore';
+import RoomContext from "../../contexts/RoomContext";
 import {Layout, LayoutPropType} from "../../settings/Layout";
 import {_t} from "../../languageHandler";
 import {haveTileForEvent} from "../views/rooms/EventTile";
-import {textForEvent} from "../../TextForEvent";
+import {hasText} from "../../TextForEvent";
 import IRCTimelineProfileResizer from "../views/elements/IRCTimelineProfileResizer";
 import DMRoomMap from "../../utils/DMRoomMap";
 import NewRoomIntro from "../views/rooms/NewRoomIntro";
@@ -151,6 +152,8 @@ export default class MessagePanel extends React.Component {
         enableFlair: PropTypes.bool,
     };
 
+    static contextType = RoomContext;
+
     constructor(props) {
         super(props);
 
@@ -380,7 +383,7 @@ export default class MessagePanel extends React.Component {
         // Always show highlighted event
         if (this.props.highlightedEventId === mxEv.getId()) return true;
 
-        return !shouldHideEvent(mxEv);
+        return !shouldHideEvent(mxEv, this.context);
     }
 
     _readMarkerForEvent(eventId, isLastEvent) {
@@ -1164,11 +1167,8 @@ class MemberGrouper {
 
     add(ev) {
         if (ev.getType() === 'm.room.member') {
-            // We'll just double check that it's worth our time to do so, through an
+            // We can ignore any events that don't actually have a message to display
-            // ugly hack. If textForEvent returns something, we should group it for
+            if (!hasText(ev)) return;
-            // rendering but if it doesn't then we'll exclude it.
-            const renderText = textForEvent(ev);
-            if (!renderText || renderText.trim().length === 0) return; // quietly ignore
         }
         this.readMarker = this.readMarker || this.panel._readMarkerForEvent(
             ev.getId(),

src/components/structures/RoomView.tsx

@@ -153,7 +153,6 @@ export interface IState {
     canPeek: boolean;
     showApps: boolean;
     isPeeking: boolean;
-    showReadReceipts: boolean;
     showRightPanel: boolean;
     // error object, as from the matrix client/server API
     // If we failed to load information about the room,
@@ -181,6 +180,12 @@ export interface IState {
     canReact: boolean;
     canReply: boolean;
     layout: Layout;
+    lowBandwidth: boolean;
+    showReadReceipts: boolean;
+    showRedactions: boolean;
+    showJoinLeaves: boolean;
+    showAvatarChanges: boolean;
+    showDisplaynameChanges: boolean;
     matrixClientIsReady: boolean;
     showUrlPreview?: boolean;
     e2eStatus?: E2EStatus;
@@ -198,8 +203,7 @@ export default class RoomView extends React.Component<IProps, IState> {
     private readonly dispatcherRef: string;
     private readonly roomStoreToken: EventSubscription;
     private readonly rightPanelStoreToken: EventSubscription;
-    private readonly showReadReceiptsWatchRef: string;
+    private settingWatchers: string[];
-    private readonly layoutWatcherRef: string;
 
     private unmounted = false;
     private permalinkCreators: Record<string, RoomPermalinkCreator> = {};
@@ -230,7 +234,6 @@ export default class RoomView extends React.Component<IProps, IState> {
             canPeek: false,
             showApps: false,
             isPeeking: false,
-            showReadReceipts: true,
             showRightPanel: RightPanelStore.getSharedInstance().isOpenForRoom,
             joining: false,
             atEndOfLiveTimeline: true,
@@ -240,6 +243,12 @@ export default class RoomView extends React.Component<IProps, IState> {
             canReact: false,
             canReply: false,
             layout: SettingsStore.getValue("layout"),
+            lowBandwidth: SettingsStore.getValue("lowBandwidth"),
+            showReadReceipts: true,
+            showRedactions: true,
+            showJoinLeaves: true,
+            showAvatarChanges: true,
+            showDisplaynameChanges: true,
             matrixClientIsReady: this.context && this.context.isInitialSyncComplete(),
             dragCounter: 0,
         };
@@ -266,9 +275,14 @@ export default class RoomView extends React.Component<IProps, IState> {
         WidgetEchoStore.on(UPDATE_EVENT, this.onWidgetEchoStoreUpdate);
         WidgetStore.instance.on(UPDATE_EVENT, this.onWidgetStoreUpdate);
 
-        this.showReadReceiptsWatchRef = SettingsStore.watchSetting("showReadReceipts", null,
+        this.settingWatchers = [
-            this.onReadReceiptsChange);
+            SettingsStore.watchSetting("layout", null, () =>
-        this.layoutWatcherRef = SettingsStore.watchSetting("layout", null, this.onLayoutChange);
+                this.setState({ layout: SettingsStore.getValue("layout") }),
+            ),
+            SettingsStore.watchSetting("lowBandwidth", null, () =>
+                this.setState({ lowBandwidth: SettingsStore.getValue("lowBandwidth") }),
+            ),
+        ];
     }
 
     private onWidgetStoreUpdate = () => {
@@ -324,9 +338,42 @@ export default class RoomView extends React.Component<IProps, IState> {
             // we should only peek once we have a ready client
             shouldPeek: this.state.matrixClientIsReady && RoomViewStore.shouldPeek(),
             showReadReceipts: SettingsStore.getValue("showReadReceipts", roomId),
+            showRedactions: SettingsStore.getValue("showRedactions", roomId),
+            showJoinLeaves: SettingsStore.getValue("showJoinLeaves", roomId),
+            showAvatarChanges: SettingsStore.getValue("showAvatarChanges", roomId),
+            showDisplaynameChanges: SettingsStore.getValue("showDisplaynameChanges", roomId),
             wasContextSwitch: RoomViewStore.getWasContextSwitch(),
         };
 
+        // Add watchers for each of the settings we just looked up
+        this.settingWatchers = this.settingWatchers.concat([
+            SettingsStore.watchSetting("showReadReceipts", null, () =>
+                this.setState({
+                    showReadReceipts: SettingsStore.getValue("showReadReceipts", roomId),
+                }),
+            ),
+            SettingsStore.watchSetting("showRedactions", null, () =>
+                this.setState({
+                    showRedactions: SettingsStore.getValue("showRedactions", roomId),
+                }),
+            ),
+            SettingsStore.watchSetting("showJoinLeaves", null, () =>
+                this.setState({
+                    showJoinLeaves: SettingsStore.getValue("showJoinLeaves", roomId),
+                }),
+            ),
+            SettingsStore.watchSetting("showAvatarChanges", null, () =>
+                this.setState({
+                    showAvatarChanges: SettingsStore.getValue("showAvatarChanges", roomId),
+                }),
+            ),
+            SettingsStore.watchSetting("showDisplaynameChanges", null, () =>
+                this.setState({
+                    showDisplaynameChanges: SettingsStore.getValue("showDisplaynameChanges", roomId),
+                }),
+            ),
+        ]);
+
         if (!initial && this.state.shouldPeek && !newState.shouldPeek) {
             // Stop peeking because we have joined this room now
             this.context.stopPeeking();
@@ -635,10 +682,6 @@ export default class RoomView extends React.Component<IProps, IState> {
             );
         }
 
-        if (this.showReadReceiptsWatchRef) {
-            SettingsStore.unwatchSetting(this.showReadReceiptsWatchRef);
-        }
-
         // cancel any pending calls to the rate_limited_funcs
         this.updateRoomMembers.cancelPendingCall();
 
@@ -646,7 +689,9 @@ export default class RoomView extends React.Component<IProps, IState> {
         // console.log("Tinter.tint from RoomView.unmount");
         // Tinter.tint(); // reset colourscheme
 
-        SettingsStore.unwatchSetting(this.layoutWatcherRef);
+        for (const watcher of this.settingWatchers) {
+            SettingsStore.unwatchSetting(watcher);
+        }
     }
 
     private onUserScroll = () => {
@@ -816,7 +861,7 @@ export default class RoomView extends React.Component<IProps, IState> {
             // update unread count when scrolled up
             if (!this.state.searchResults && this.state.atEndOfLiveTimeline) {
                 // no change
-            } else if (!shouldHideEvent(ev)) {
+            } else if (!shouldHideEvent(ev, this.state)) {
                 this.setState((state, props) => {
                     return {numUnreadMessages: state.numUnreadMessages + 1};
                 });

src/components/structures/TimelinePanel.js

@@ -26,6 +26,7 @@ import {EventTimeline} from "matrix-js-sdk/src/models/event-timeline";
 import {TimelineWindow} from "matrix-js-sdk/src/timeline-window";
 import { _t } from '../../languageHandler';
 import {MatrixClientPeg} from "../../MatrixClientPeg";
+import RoomContext from "../../contexts/RoomContext";
 import UserActivity from "../../UserActivity";
 import Modal from "../../Modal";
 import dis from "../../dispatcher/dispatcher";
@@ -125,6 +126,8 @@ class TimelinePanel extends React.Component {
         alwaysShowTimestamps: PropTypes.bool,
     }
 
+    static contextType = RoomContext;
+
     // a map from room id to read marker event timestamp
     static roomReadMarkerTsMap = {};
 
@@ -1288,7 +1291,7 @@ class TimelinePanel extends React.Component {
 
             const shouldIgnore = !!ev.status || // local echo
                 (ignoreOwn && ev.sender && ev.sender.userId == myUserId);   // own message
-            const isWithoutTile = !haveTileForEvent(ev) || shouldHideEvent(ev);
+            const isWithoutTile = !haveTileForEvent(ev) || shouldHideEvent(ev, this.context);
 
             if (isWithoutTile || !node) {
                 // don't start counting if the event should be ignored,

src/components/views/avatars/BaseAvatar.tsx

@@ -22,6 +22,7 @@ import classNames from 'classnames';
 import * as AvatarLogic from '../../../Avatar';
 import SettingsStore from "../../../settings/SettingsStore";
 import AccessibleButton from '../elements/AccessibleButton';
+import RoomContext from "../../../contexts/RoomContext";
 import MatrixClientContext from "../../../contexts/MatrixClientContext";
 import {useEventEmitter} from "../../../hooks/useEventEmitter";
 import {toPx} from "../../../utils/units";
@@ -44,12 +45,12 @@ interface IProps {
     className?: string;
 }
 
-const calculateUrls = (url, urls) => {
+const calculateUrls = (url, urls, lowBandwidth) => {
     // work out the full set of urls to try to load. This is formed like so:
     // imageUrls: [ props.url, ...props.urls ]
 
     let _urls = [];
-    if (!SettingsStore.getValue("lowBandwidth")) {
+    if (!lowBandwidth) {
         _urls = urls || [];
 
         if (url) {
@@ -63,7 +64,13 @@ const calculateUrls = (url, urls) => {
 };
 
 const useImageUrl = ({url, urls}): [string, () => void] => {
-    const [imageUrls, setUrls] = useState<string[]>(calculateUrls(url, urls));
+    // Since this is a hot code path and the settings store can be slow, we
+    // use the cached lowBandwidth value from the room context if it exists
+    const roomContext = useContext(RoomContext);
+    const lowBandwidth = roomContext ?
+        roomContext.lowBandwidth : SettingsStore.getValue("lowBandwidth");
+
+    const [imageUrls, setUrls] = useState<string[]>(calculateUrls(url, urls, lowBandwidth));
     const [urlsIndex, setIndex] = useState<number>(0);
 
     const onError = useCallback(() => {
@@ -71,7 +78,7 @@ const useImageUrl = ({url, urls}): [string, () => void] => {
     }, []);
 
     useEffect(() => {
-        setUrls(calculateUrls(url, urls));
+        setUrls(calculateUrls(url, urls, lowBandwidth));
         setIndex(0);
     }, [url, JSON.stringify(urls)]); // eslint-disable-line react-hooks/exhaustive-deps
 

src/components/views/rooms/EventTile.tsx

@@ -25,7 +25,7 @@ import { RoomMember } from "matrix-js-sdk/src/models/room-member";
 
 import ReplyThread from "../elements/ReplyThread";
 import { _t } from '../../../languageHandler';
-import * as TextForEvent from "../../../TextForEvent";
+import { hasText } from "../../../TextForEvent";
 import * as sdk from "../../../index";
 import dis from '../../../dispatcher/dispatcher';
 import SettingsStore from "../../../settings/SettingsStore";
@@ -1210,7 +1210,7 @@ export function haveTileForEvent(e) {
     const handler = getHandlerTile(e);
     if (handler === undefined) return false;
     if (handler === 'messages.TextualEvent') {
-        return TextForEvent.textForEvent(e) !== '';
+        return hasText(e);
     } else if (handler === 'messages.RoomCreate') {
         return Boolean(e.getContent()['predecessor']);
     } else {

src/contexts/RoomContext.ts

@@ -31,7 +31,6 @@ const RoomContext = createContext<IState>({
     canPeek: false,
     showApps: false,
     isPeeking: false,
-    showReadReceipts: true,
     showRightPanel: true,
     joining: false,
     atEndOfLiveTimeline: true,
@@ -41,6 +40,12 @@ const RoomContext = createContext<IState>({
     canReact: false,
     canReply: false,
     layout: Layout.Group,
+    lowBandwidth: false,
+    showReadReceipts: true,
+    showRedactions: true,
+    showJoinLeaves: true,
+    showAvatarChanges: true,
+    showDisplaynameChanges: true,
     matrixClientIsReady: false,
     dragCounter: 0,
 });

src/i18n/strings/en_EN.json

@@ -556,8 +556,8 @@
     "%(senderName)s made future room history visible to all room members.": "%(senderName)s made future room history visible to all room members.",
     "%(senderName)s made future room history visible to anyone.": "%(senderName)s made future room history visible to anyone.",
     "%(senderName)s made future room history visible to unknown (%(visibility)s).": "%(senderName)s made future room history visible to unknown (%(visibility)s).",
-    "%(userId)s from %(fromPowerLevel)s to %(toPowerLevel)s": "%(userId)s from %(fromPowerLevel)s to %(toPowerLevel)s",
     "%(senderName)s changed the power level of %(powerLevelDiffText)s.": "%(senderName)s changed the power level of %(powerLevelDiffText)s.",
+    "%(userId)s from %(fromPowerLevel)s to %(toPowerLevel)s": "%(userId)s from %(fromPowerLevel)s to %(toPowerLevel)s",
     "%(senderName)s changed the pinned messages for the room.": "%(senderName)s changed the pinned messages for the room.",
     "%(widgetName)s widget modified by %(senderName)s": "%(widgetName)s widget modified by %(senderName)s",
     "%(widgetName)s widget added by %(senderName)s": "%(widgetName)s widget added by %(senderName)s",

src/shouldHideEvent.ts

@@ -17,6 +17,7 @@
 import {MatrixEvent} from "matrix-js-sdk/src/models/event";
 
 import SettingsStore from "./settings/SettingsStore";
+import {IState} from "./components/structures/RoomView";
 
 interface IDiff {
     isMemberEvent: boolean;
@@ -47,11 +48,18 @@ function memberEventDiff(ev: MatrixEvent): IDiff {
     return diff;
 }
 
-export default function shouldHideEvent(ev: MatrixEvent): boolean {
+/**
-    // Wrap getValue() for readability. Calling the SettingsStore can be
+ * Determines whether the given event should be hidden from timelines.
-    // fairly resource heavy, so the checks below should avoid hitting it
+ * @param ev The event
-    // where possible.
+ * @param ctx An optional RoomContext to pull cached settings values from to avoid
-    const isEnabled = (name) => SettingsStore.getValue(name, ev.getRoomId());
+ *     hitting the settings store
+ */
+export default function shouldHideEvent(ev: MatrixEvent, ctx?: IState): boolean {
+    // Accessing the settings store directly can be expensive if done frequently,
+    // so we should prefer using cached values if a RoomContext is available
+    const isEnabled = ctx ?
+        name => ctx[name] :
+        name => SettingsStore.getValue(name, ev.getRoomId());
 
     // Hide redacted events
     if (ev.isRedacted() && !isEnabled('showRedactions')) return true;

test/components/structures/MessagePanel-test.js

@@ -51,8 +51,20 @@ class WrappedMessagePanel extends React.Component {
     };
 
     render() {
+        const roomContext = {
+            room,
+            roomId: room.roomId,
+            canReact: true,
+            canReply: true,
+            showReadReceipts: true,
+            showRedactions: false,
+            showJoinLeaves: false,
+            showAvatarChanges: false,
+            showDisplaynameChanges: true,
+        };
+
         return <MatrixClientContext.Provider value={client}>
-            <RoomContext.Provider value={{ canReact: true, canReply: true, room, roomId: room.roomId }}>
+            <RoomContext.Provider value={roomContext}>
                 <MessagePanel room={room} {...this.props} resizeNotifier={this.state.resizeNotifier} />
             </RoomContext.Provider>
         </MatrixClientContext.Provider>;