273ba62e0e
Something was bothering me a bit with the discussion around sqrt's being slow. Looks like `Math.hypot` has a performance cost associated with it. Looking at the Chromium source code: https://chromium.googlesource.com/v8/v8/+/4.3.21/src/math.js?autodive=0%2F%2F#19 and https://source.chromium.org/chromium/chromium/src/+/main:v8/src/builtins/math.tq;l=36?q=math&sq=&ss=chromium%2Fchromium%2Fsrc:v8%2Fsrc%2F it looks like maybe we'd be avoiding the multiple arguments that can be passed into Math.hypot which is maybe the source of the perf hit. Also, interestingly in `math.tq` you can see it doing this funky sqrt calculation: `Float64Sqrt((a / max) * (a / max) + (b / max) * (b / max)) * max` - I think that possibly is trying to avoid some overflow in some cases with bigger numbers, but also possibly with a perf hit. [edit]: OK, actually on Firefox, doing sqrt seems slower - but digging more into this, it looks like doing `** 0.5` instead of `sqrt` is much faster. More related articles: - https://stackoverflow.com/questions/71898044/why-is-math-hypot-so-slow - https://stackoverflow.com/questions/3764978/why-hypot-function-is-so-slow - https://www.reddit.com/r/javascript/comments/wk3e57/askjs_why_mathsqrt_is_so_slow_in_firefox/ [edit again!] looks like this is being fixed in the latest Chrome! https://blog.seokho.dev/development/2024/03/18/V8-optimize-MathHypot.html ``` ┌─────────┬───────┬─────────┬─────────┬─────────┬────────┐ │ (index) │ Cold │ Slowest │ Fastest │ Average │ Total │ ├─────────┼───────┼─────────┼─────────┼─────────┼────────┤ │ old │ 13.39 │ 10.07 │ 9.69 │ 9.98 │ 998.57 │ │ sqrt │ 8.19 │ 6.66 │ 6.61 │ 6.67 │ 667.6 │ │ pow 0.5 │ 1.89 │ 0.28 │ 0.28 │ 0.3 │ 29.79 │ │ new │ 1.64 │ 0.28 │ 0.28 │ 0.29 │ 28.95 │ └─────────┴───────┴─────────┴─────────┴─────────┴────────┘ ``` ### Change Type <!-- ❗ Please select a 'Scope' label ❗️ --> - [x] `sdk` — Changes the tldraw SDK - [ ] `dotcom` — Changes the tldraw.com web app - [ ] `docs` — Changes to the documentation, examples, or templates. - [ ] `vs code` — Changes to the vscode plugin - [ ] `internal` — Does not affect user-facing stuff <!-- ❗ Please select a 'Type' label ❗️ --> - [ ] `bugfix` — Bug fix - [ ] `feature` — New feature - [x] `improvement` — Improving existing features - [ ] `chore` — Updating dependencies, other boring stuff - [ ] `galaxy brain` — Architectural changes - [ ] `tests` — Changes to any test code - [ ] `tools` — Changes to infrastructure, CI, internal scripts, debugging tools, etc. - [ ] `dunno` — I don't know |
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