2020567 - 13.35 - 6.46% perf_reftest coalesce-2.html + 2 more (Linux) regression on Tue February 24 2026

Status: NEW

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

Description

[Treeherder Bug Filer]

Perfherder has detected a talos performance regression from push 0d3fd295c1db2bbd7221f932cce34ae9043ebf3f. 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]
13%	perf_reftest coalesce-2.html (doc)	linux1804-64-shippable-qr	e10s fission stylo webrender-sw	25.77 ms -> 29.21 ms
12%	perf_reftest coalesce-2.html (doc)	linux1804-64-shippable-qr	e10s fission stylo webrender	26.52 ms -> 29.60 ms
6%	perf_reftest coalesce-1.html (doc)	linux1804-64-shippable-qr	e10s fission stylo webrender-sw	77.56 ms -> 82.58 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 48863 (See documentation link for details).
• Profiling jobs: Trigger jobs from Treeherder job view or request them from [e-mail].

Comment 1

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

Set release status flags based on info from the regressing bug 2017005

Comment 2

[Emilio Cobos Álvarez [:emilio]]

This is a microbenchmark that doesn't matter as much compared to the speedometer improvements from bug 2017005. Bug 2018923 would give this one back tho.

Comment 3

[Henri Sivonen (:hsivonen)]

Marking S3 to prioritize Speedometer 3.