by tasn 5 hours ago
Does anyone know why Firefox/Servo are so slow compared to the rest?
A few big things and lots of small things.
Big performance wins recently optimizing some core operations:
https://bugzilla.mozilla.org/show_bug.cgi?id=1994067 https://bugzilla.mozilla.org/show_bug.cgi?id=1995626
which brings it near chrome performance without the new v8 optimizations.
Still more work to do, including avoiding extra copies just like v8, and exploring more simd etc. Generic slow items for toBase64 and fromBase64: https://bugzilla.mozilla.org/show_bug.cgi?id=2003299 https://bugzilla.mozilla.org/show_bug.cgi?id=2003305
extra copying of results: https://bugzilla.mozilla.org/show_bug.cgi?id=2003461 https://bugzilla.mozilla.org/show_bug.cgi?id=1996197
No reason all browsers would not be able to be similar in performance eventually. Pleased this was noticed and being worked on by both v8 and Firefox team
Thanks for sharing!
Incredible that FF is even slower than a JS only implementation running in FF.
Mozilla's "privacy" image prevents them from knowing what their browser actually does in the wild, while Google collects CPU time profiles from user devices, comprehensively, and hammers down the hotspots they find, and that refinement has been going on for many years.
Even if true (and I agree with sibling that I don't think that it is), base64 encoding/decoding feels like one of those things you'd have a micro benchmark for regardless. It's also shocking that the gap is so wide, as I feel like people working on such things would start with a fairly optimized v1.
I wonder if this is why Firefox feels so sluggish with some more complex SPAs.
That’s nonsense. Firefox has telemetry built in, it’s just that you can opt out of it. Your answer doesn’t explain why at all but instead just takes a wild guess at what might have happened. You don’t know if this was discovered in Chrome or in some other use of V8. Or maybe it was always fast in Chrome! What a weird non-answer.