2049975 - 23.68 - 2.98% Base Content Heap Unclassified + 8 more (Linux, OSX, Windows) regression on Wed June 17 2026

Status: RESOLVED DUPLICATE of bug 2049092

(Core :: Preferences: Backend, defect)

Description

[Treeherder Bug Filer]

Perfherder has detected a awsy performance regression from push a98da40f8e32b831a0d25b3c46a22c23be177cad. 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]
24%	Base Content Heap Unclassified (doc)	windows11-64-25h2-shippable	fission	2,057,246.00 bytes -> 2,544,358.67 bytes
17%	Base Content Heap Unclassified (doc)	macosx1470-64-shippable	fission	2,748,349.33 bytes -> 3,220,901.33 bytes
16%	Base Content Heap Unclassified (doc)	linux2404-64-shippable	fission	2,890,422.00 bytes -> 3,361,865.33 bytes
7%	Base Content Explicit (doc)	macosx1470-64-shippable	fission	7,493,405.33 bytes -> 8,009,103.33 bytes
7%	Base Content Explicit (doc)	windows11-64-25h2-shippable	fission	7,782,279.33 bytes -> 8,311,371.33 bytes
6%	Base Content Explicit (doc)	linux2404-64-shippable	fission	7,969,708.00 bytes -> 8,486,367.33 bytes
6%	Base Content Resident Unique Memory (doc)	linux2404-64-shippable	fission	8,211,456.00 bytes -> 8,720,725.33 bytes
6%	Heap Unclassified (doc)	macosx1470-64-shippable	fission tp6	152,178,304.55 bytes -> 161,056,097.85 bytes
3%	Base Content Resident Unique Memory (doc)	macosx1470-64-shippable	fission	17,371,136.00 bytes -> 17,888,597.33 bytes

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 51014 (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 2016900

Comment 3

[Jens Stutte [:jstutte]]

Thanks Mayank for making me aware earlier!