2090871 - 7.83 - 1.01% jetstream3 first-inspector-code-load-First + 13 more (OSX, Windows) regression on Fri November 6 2026

Status: RESOLVED FIXED

(Firefox Build System :: Toolchains, defect)

Description

[Performance Sheriff Bot]

Perfherder has detected a browsertime performance regression from push ccda191f91b8fec879e774d5ec23d8509b1c1f18. We would like to inform you that we are requesting an immediate back out from [e-mail] of the current patch due to performance regressions on the following critical test(s): speedometer3 score windows11-64-24h2-shippable, speedometer3 TodoMVC-JavaScript-ES5/total linux2404-64-shippable, speedometer3 windows11-64-24h2-shippable, speedometer3 total windows11-64-24h2-shippable, speedometer3 score macosx1500-aarch64-shippable, speedometer3 macosx1500-aarch64-shippable, speedometer3 TodoMVC-WebComponents/total windows11-64-24h2-shippable, speedometer3 TodoMVC-Lit-Complex-DOM/total windows11-64-24h2-shippable, speedometer3 TodoMVC-JavaScript-ES5/total windows11-64-24h2-shippable, speedometer3 TodoMVC-Backbone/total windows11-64-24h2-shippable, speedometer3 TodoMVC-Angular-Complex-DOM/total windows11-64-24h2-shippable, speedometer3 NewsSite-Nuxt/total windows11-64-24h2-shippable, speedometer3 NewsSite-Nuxt/total macosx1500-aarch64-shippable, speedometer3 NewsSite-Next/total windows11-64-24h2-shippable, speedometer3 NewsSite-Next/total macosx1500-aarch64-shippable, speedometer3 Editor-TipTap/total windows11-64-24h2-shippable, speedometer3 Charts-observable-plot/total windows11-64-24h2-shippable.

Please review our regression policy for additional details regarding the reasons for the immediate backout.

Regression	Test	Platform	Options	Absolute values [old vs new]	Performance Profiles
8%	jetstream3 first-inspector-code-load-First (doc)	macosx1500-aarch64-shippable	fission webrender	11.72 -> 12.64
5%	jetstream3 multi-inspector-code-load-First (doc)	macosx1500-aarch64-shippable	fission webrender	11.90 -> 12.54
3%	speedometer3 TodoMVC-WebComponents/total (doc)	windows11-64-24h2-shippable	fission webrender	16.11 -> 16.59
2%	speedometer3 NewsSite-Next/total (doc)	windows11-64-24h2-shippable	fission webrender	112.30 -> 114.55
2%	speedometer3 TodoMVC-Lit-Complex-DOM/total (doc)	windows11-64-24h2-shippable	fission webrender	19.62 -> 20.00
2%	speedometer3 TodoMVC-Backbone/total (doc)	windows11-64-24h2-shippable	fission webrender	29.01 -> 29.57
2%	speedometer3 Editor-TipTap/total (doc)	windows11-64-24h2-shippable	fission webrender	50.70 -> 51.66
2%	speedometer3 total (doc)	windows11-64-24h2-shippable	fission webrender	920.56 -> 936.21
1%	speedometer3 Charts-observable-plot/total (doc)	windows11-64-24h2-shippable	fission webrender	45.79 -> 46.45
1%	speedometer3 (doc)	windows11-64-24h2-shippable	fission webrender	26.36 -> 25.98
1%	speedometer3 score (doc)	windows11-64-24h2-shippable	fission webrender	26.36 -> 25.98
1%	speedometer3 TodoMVC-JavaScript-ES5/total (doc)	windows11-64-24h2-shippable	fission webrender	34.19 -> 34.64
1%	speedometer3 TodoMVC-Angular-Complex-DOM/total (doc)	windows11-64-24h2-shippable	fission webrender	43.13 -> 43.65
1%	speedometer3 NewsSite-Nuxt/total (doc)	windows11-64-24h2-shippable	fission webrender	86.43 -> 87.30

Improvement	Test	Platform	Options	Absolute values [old vs new]	Performance Profiles
1%	speedometer3 TodoMVC-JavaScript-ES5/total (doc)	linux2404-64-shippable	fission webrender	65.37 ms -> 64.47 ms	Before/After
1%	speedometer3 NewsSite-Next/total (doc)	macosx1500-aarch64-shippable	fission webrender	43.80 ms -> 43.37 ms
1%	speedometer3 NewsSite-Nuxt/total (doc)	macosx1500-aarch64-shippable	fission webrender	35.75 ms -> 35.41 ms
1%	speedometer3 (doc)	macosx1500-aarch64-shippable	fission webrender	52.66 score -> 53.01 score
1%	speedometer3 score (doc)	macosx1500-aarch64-shippable	fission webrender	52.66 score -> 53.01 score

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 54206 (See documentation link for details).
• Test locally: To run the tests locally use ./mach perftest 54206
• 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 2053035

Comment 2

[Cosmin Sabou [:CosminS]]

Backed out the regressor in https://hg.mozilla.org/integration/autoland/rev/a5477bf93a643a43e30ab64fd23872582f971f39

Comment 3

[Donal Meehan [:dmeehan]]

Resolving since the regressor was backed out