2032120 - 2.78 - 2.1% speedometer3 TodoMVC-Preact-Complex-DOM/Adding100Items/Sync + 2 more (OSX) regression on Tue April 14 2026

Status: RESOLVED WONTFIX

(Core :: DOM: UI Events & Focus Handling, defect)

Description

[Treeherder Bug Filer]

Perfherder has detected a browsertime performance regression from push 9b37300e1d86e36411e34da7fb4a660983c84436. As author of one of the patches included in that push, we need your help to address this regression.

Please acknowledge, and begin investigating this alert within 3 business days, or the patch(es) may be backed out in accordance with our regression policy.

Regression	Test	Platform	Options	Absolute values [old vs new]	Performance Profiles
3%	speedometer3 TodoMVC-Preact-Complex-DOM/Adding100Items/Sync (doc)	macosx1500-aarch64-shippable	fission webrender	0.45 -> 0.46	Before/After
3%	speedometer3 TodoMVC-Svelte-Complex-DOM/Adding100Items/Sync (doc)	macosx1500-aarch64-shippable	fission webrender	0.92 -> 0.95	Before/After
2%	speedometer3 TodoMVC-Vue/Adding100Items/Sync (doc)	macosx1500-aarch64-shippable	fission webrender	1.19 -> 1.22	Before/After

Support & Actionable Steps

For questions, please contact [e-mail]. You can also find help on Slack (#perf-help) or Matrix (#perftest).

Action guide details:

• See the guide to handling regression bugs for investigation steps.
• Review the alert summary for affected tests, graphs, and comparisons.
• Check the PerfCompare results.
• Tests on Try: Run all tests using ./mach try perf --alert 49748 (See documentation link for details).
• Profiling jobs: Trigger jobs from Treeherder job view or request them from [e-mail].

Comment 1

[BugBot [:suhaib / :marco]]

Set release status flags based on info from the regressing bug 2023374

Comment 2

[mozilla.7fhrv]

It might improve performance to change WeakFrame to raw pointer.
I'll try it.

Comment 3

[mozilla.7fhrv]

I couldn't replicate 2.x% on local.
And, logics of this patch (such as ClearFrameRefs) does not appear in the profile.

I wonder there is a way to find the cause.
and to be honest, I have no idea why this patch affects as much as 3%.

Comment 4

[Olli Pettay [:smaug][[e-mail]]]

It is only in some subtests.
Hmm, do we end up triggering more IPC traffic. That might be the reason

Comment 5

[mozilla.7fhrv]

PVSync::Msg_Notify and mozilla::ipc::MessageChannel::MessageTask::Run are almost identical (before: 116 vs after: 110 + 6) I suppose.
I agree that IPC (by LeaveLink) is likely increase, but I couldn't find it in the profile.

Comment 6

[BugBot [:suhaib / :marco]]

Set release status flags based on info from the regressing bug 2023374

Comment 7

[BugBot [:suhaib / :marco]]

It has been over 7 days with no activity on this performance regression.

:mozilla.7fhrv, since you are the author of the regressor, bug 2023374, which triggered this performance alert, could you please provide a progress update?

If this regression is something that fixes a bug, changes the baseline of the regression metrics, or otherwise will not be fixed, please consider closing it as WONTFIX. See this documentation for more information on how to handle regressions.

For additional information/help, please needinfo the performance sheriff who filed this alert (they can be found in comment #0), or reach out in #perftest, or #perfsheriffs on Element.

For more information, please visit BugBot documentation.

Comment 8

[mozilla.7fhrv]

Since I couldn't reproduce and haven't found the cause, I'm considering closing with WONTFIX or WORKSFORME if it's a fix-optional.
Is it ok?

Comment 9

[BugBot [:suhaib / :marco]]

It has been over 7 days with no activity on this performance regression.

:mozilla.7fhrv, since you are the author of the regressor, bug 2023374, which triggered this performance alert, could you please provide a progress update?

If this regression is something that fixes a bug, changes the baseline of the regression metrics, or otherwise will not be fixed, please consider closing it as WONTFIX. See this documentation for more information on how to handle regressions.

For additional information/help, please needinfo the performance sheriff who filed this alert (they can be found in comment #0), or reach out in #perftest, or #perfsheriffs on Element.

For more information, please visit BugBot documentation.

Comment 10

[mozilla.7fhrv]

I don't have the permission, so could someone set WORKSFORME for me?