2016120 - 6.05% cpstartup content-process-startup (Linux) regression on Wed January 28 2026

Status: RESOLVED WONTFIX

(Firefox :: New Tab Page, defect)

Description

[Treeherder Bug Filer]

Perfherder has detected a talos performance regression from push 94794eabf67cbd569d05bb5fb3b2a41c4cbe308b. 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]
6%	cpstartup content-process-startup (doc)	linux1804-64-shippable-qr	e10s fission stylo webrender-sw	56.50 ms -> 59.92 ms

Improvement	Test	Platform	Options	Absolute values [old vs new]
9%	pdfpaint issue13931.pdf (doc)	macosx1470-64-shippable	e10s fission stylo webrender	1,007.15 ms -> 912.49 ms

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 48354 (See documentation link for details).
• Profiling jobs: Trigger jobs from Treeherder job view or request them from [e-mail].

Comment 1

[Mike Conley (:mconley) (:⚙️)]

This isn't completely unexpected, I guess - we're intentionally choosing not to cache things that probably shouldn't have been cached in the first place.