1959951 - 0.25% Base Content JS (Windows) regression on Fri April 4 2025

Status: RESOLVED WONTFIX

(Core :: DOM: Core & HTML, defect)

Description

[Treeherder Bug Filer]

Perfherder has detected a awsy performance regression from push 44703bab2416332ba7502df9a0e436b83def9d39. 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)
0.25%	Base Content JS	windows11-64-24h2-shippable	fission	1,547,466.00 -> 1,551,360.00

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 44644

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 1958287

Comment 2

[Jan Jaeschke [:jjaschke]]

Bug 1958287 enables hidden=until-found (Bug 1761043) on Nightly. This feature requires an additional DOM traversal during scrolling to a fragment. That is the only part of the patches in bug 1761043 which I assume could have a performance impact. But I don't see a way to improve that.

Alex, unless you disagree or I misunderstand the results, I would close this.

Comment 3

[Alex Finder]

(In reply to Jan Jaeschke [:jjaschke] from comment #2)

Bug 1958287 enables hidden=until-found (Bug 1761043) on Nightly. This feature requires an additional DOM traversal during scrolling to a fragment. That is the only part of the patches in bug 1761043 which I assume could have a performance impact. But I don't see a way to improve that.

Alex, unless you disagree or I misunderstand the results, I would close this.

Hi Jan! Your suggestion makes sense, you can close the bug as WONTFIX, and I'll update the linked alert summary. Thanks!