2001092 - 19.59 - 6.71% jetstream3 doxbee-promise-First / jetstream3 web-ssr-Worst + 12 more (Android, Linux, OSX, Windows) regression on Thu November 13 2025

Status: RESOLVED FIXED

(Core :: JavaScript Engine, defect)

Description

[Treeherder Bug Filer]

Perfherder has detected a browsertime performance regression from push 13d65a94e4cf6a7bb3ec9c239156a090d0884619. 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)	Performance Profiles
20%	jetstream3 doxbee-promise-First	macosx1500-aarch64-shippable	fission webrender	85.41 -> 102.14	Before/After
16%	jetstream3 doxbee-promise-Average	windows11-64-24h2-shippable	fission webrender	124.89 -> 144.48	Before/After
14%	jetstream3 doxbee-promise-Average	macosx1500-aarch64-shippable	fission webrender	86.86 -> 99.30	Before/After
13%	jetstream3 doxbee-async-Average	windows11-64-24h2-shippable	fission webrender	62.34 -> 70.63	Before/After
13%	jetstream3 doxbee-promise-Geometric	macosx1500-aarch64-shippable	fission webrender	53.12 -> 46.31	Before/After
10%	jetstream3 doxbee-promise-First	linux1804-64-shippable-qr	fission webrender	267.57 -> 295.43	Before/After
10%	jetstream3 doxbee-async-Average	macosx1500-aarch64-shippable	fission webrender	43.36 -> 47.81	Before/After
8%	jetstream3 web-ssr-First	linux1804-64-shippable-qr	fission webrender	66.88 -> 72.04	Before/After
8%	jetstream3 doxbee-promise-Average	android-hw-a55-14-0-aarch64-shippable	webrender	316.67 -> 340.74
8%	jetstream3 doxbee-promise-Average	android-hw-a55-14-0-aarch64-shippable	fission webrender	315.77 -> 339.65
7%	jetstream3 async-fs-Average	windows11-64-24h2-shippable	fission webrender	19.91 -> 21.40	Before/After
7%	jetstream3 doxbee-promise-Average	linux1804-64-shippable-qr	fission webrender	270.95 -> 290.11	Before/After
7%	jetstream3 doxbee-promise-Geometric	android-hw-a55-14-0-aarch64-shippable	fission webrender	14.53 -> 13.55
7%	jetstream3 web-ssr-Worst	macosx1500-aarch64-shippable	fission webrender	17.15 -> 18.30	Before/After

Improvements:

Ratio	Test	Platform	Options	Absolute values (old vs new)	Performance Profiles
23%	jetstream3 tsf-wasm-Worst	macosx1500-aarch64-shippable	fission webrender	16.63 -> 12.76	Before/After
17%	jetstream3 tsf-wasm-First	macosx1500-aarch64-shippable	fission webrender	22.31 -> 18.44	Before/After
16%	jetstream3 tsf-wasm-Geometric	macosx1500-aarch64-shippable	fission webrender	300.10 -> 349.56	Before/After

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 47463

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 1997192

Comment 2

[Matthew Gaudet (he/him) [:mgaudet]]

Thank you. I will request a backout of the regressing patch.

(See Bug 1990842 for a discussion of why this wasn't the expected performance win)

Comment 3

[Matthew Gaudet (he/him) [:mgaudet]]

This will be resolved by the backout.

Comment 4

[Ryan VanderMeulen [:RyanVM]]

Fixed by backout.