1991424 - 35.57% browser_addManyIds.js A11Y_TotalTime (Windows) regression on Tue September 23 2025

Status: RESOLVED DUPLICATE of bug 1987997

(Core :: Layout: Text and Fonts, defect, P3)

Description

[Treeherder Bug Filer]

Perfherder has detected a mozperftest performance regression from push ff7bf296a64e46a6e33cc3cd0ebe683d8ae8556f. 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. Our guide to handling regression bugs has information about how you can proceed with this investigation.

If you have any questions or need any help with the investigation, please reach out to [e-mail]. Alternatively, you can find help on Slack by joining #perf-help, and on Matrix you can find help by joining #perftest.

Regressions:

Ratio	Test	Platform	Options	Absolute values (old vs new)
36%	browser_addManyIds.js A11Y_TotalTime	windows11-64-24h2-shippable		41.17 -> 55.82

Details of the alert can be found in the alert summary, including links to graphs and comparisons for each of the affected tests.

If you need the profiling jobs you can trigger them yourself from treeherder job view or ask [e-mail] to do that for you.

You can run all of these tests on try with ./mach try perf --alert 46927

The following documentation link provides more information about this command.

Comment 1

[BugBot [:suhaib / :marco/ :calixte]]

Set release status flags based on info from the regressing bug 1988596

Comment 2

[Ting-Yu Lin [:TYLin] (PST, UTC-8)]

This is a nightly-only regression.

Here is a performance comparison of current Nightly vs Nightly + bug 1987997.

With Bug 1987997 lands, it will bring browser_addManyIds.js A11Y_TotalTime's performance on par with Nightly builds with text-autospace disabled.

Comment 3

[BugBot [:suhaib / :marco/ :calixte]]

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

:TYLin, since you are the author of the regressor, bug 1988596, 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 4

[Ting-Yu Lin [:TYLin] (PST, UTC-8)]

I'm planning to land bug 1987997 in Firefox 146, which can fix this regression. This bug won't affect Firefox 145 once it becomes beta version.

Comment 5

[Ting-Yu Lin [:TYLin] (PST, UTC-8)]

This regression is fixed by bug 1987997. Resolving as a duplicate.