1958542 - 8.59 - 7.24% fandom loadtime / fandom loadtime (Windows) regression on Wed March 26 2025

Status: RESOLVED WONTFIX

(Core :: Privacy: Anti-Tracking, defect, P3)

Description

[Treeherder Bug Filer]

Perfherder has detected a browsertime performance regression from push 67622b583ab4673683025db917c7152bd04e2178. 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)	Performance Profiles
9%	fandom loadtime	windows11-64-24h2-shippable	bytecode-cached fission warm webrender	102.01 -> 110.77	Before/After
7%	fandom loadtime	windows11-64-24h2-shippable	bytecode-cached fission warm webrender	102.76 -> 110.20	Before/After

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 44628

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 1901602

Comment 2

[Dianna Smith [:diannaS]]

:timhuang can you assign a severity here in order to assess tracking for 138?

Comment 3

[William Wen (:wwen)]

From the profiles it looks like the performance regression is caused by one extra onBeforeRequest event that the webcompat extension has to handle. This makes sense since the webcompat extension now checks the request from platform.twitter.com because of the new shim added.

Comment 4

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

It has been over 7 days with no activity on this performance regression.

:wwen, since you are the author of the regressor, bug 1901602, which triggered this performance alert, could you please provide a progress update?

If this regression is something that fixes a bug, changes the baseline of the regression metrics, or otherwise will not be fixed, please consider closing it as WONTFIX. See this documentation for more information on how to handle regressions.

For additional information/help, please needinfo the performance sheriff who filed this alert (they can be found in comment #0), or reach out in #perftest, or #perfsheriffs on Element.

For more information, please visit BugBot documentation.