2009404 - 612.75 - 6.97% damp custom.jsdebugger.project-search.DAMP / damp custom.netmonitor.manyrequests.requestsFinished.DAMP + 6 more (Linux, OSX, Windows) regression on Tue January 6 2026

Status: NEW

(DevTools :: Debugger, defect)

Description

[Treeherder Bug Filer]

Perfherder has detected a devtools performance regression from push 7fbb366e32836ea63d042a185b4a73bc5e6f300f. 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)
613%	damp custom.jsdebugger.project-search.DAMP	linux1804-64-shippable-qr	e10s fission stylo webrender	358.79 -> 2,557.29
485%	damp custom.jsdebugger.project-search.DAMP	macosx1470-64-shippable	e10s fission stylo webrender	404.42 -> 2,365.03
444%	damp custom.jsdebugger.project-search.DAMP	windows11-64-24h2-shippable	e10s fission stylo webrender	265.99 -> 1,447.73
53%	damp custom.netmonitor.manyrequests.togglepanel	windows11-64-24h2-shippable	e10s fission stylo webrender	163.44 -> 249.59
22%	damp custom.jsdebugger.close.DAMP	macosx1470-64-shippable	e10s fission stylo webrender	17.10 -> 20.78
20%	damp custom.jsdebugger.close.DAMP	macosx1470-64-shippable	e10s fission stylo webrender	17.12 -> 20.57
10%	damp custom.jsdebugger.close.DAMP	linux1804-64-shippable-qr	e10s fission stylo webrender	26.60 -> 29.13
7%	damp custom.netmonitor.manyrequests.requestsFinished.DAMP	linux1804-64-shippable-qr	e10s fission stylo webrender	3,033.86 -> 3,245.47

Improvements:

Ratio	Test	Platform	Options	Absolute values (old vs new)
92%	damp simple.netmonitor.exportHar	linux1804-64-shippable-qr	e10s fission stylo webrender	43.84 -> 3.71
75%	damp custom.jsdebugger.open-large-minified-file.DAMP	linux1804-64-shippable-qr	e10s fission stylo webrender	250.22 -> 62.55
55%	damp source-map-loader.init.DAMP	macosx1470-64-shippable	e10s fission stylo webrender	68.81 -> 31.08
54%	damp source-map-loader.init.DAMP	windows11-64-24h2-shippable	e10s fission stylo webrender	66.75 -> 31.01
48%	damp browser-toolbox.start-process.DAMP	windows11-64-24h2-shippable	e10s fission stylo webrender	20.94 -> 10.94
...	...	...	...	...
3%	damp custom.jsdebugger.stepOver.big-bundle.DAMP	linux1804-64-shippable-qr	e10s fission stylo webrender	678.36 -> 660.11

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 48159

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 2006393