1960866 - 12.18 - 10.18% bing-search FirstVisualChange / bing-search fcp + 2 more (Windows) regression on Wed April 2 2025

Status: RESOLVED FIXED

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

Description

[Treeherder Bug Filer]

Perfherder has detected a browsertime performance regression from push 05d67bda9966f8335d5cff3849d99ebfc8803a14. 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
12%	bing-search FirstVisualChange	windows11-64-24h2-shippable	bytecode-cached cold fission webrender	101.36 -> 113.70	Before/After
12%	bing-search fcp	windows11-64-24h2-shippable	cold fission webrender	76.03 -> 85.23	Before/After
11%	bing-search fcp	windows11-64-24h2-shippable	bytecode-cached cold fission webrender	75.67 -> 84.32	Before/After
10%	bing-search fcp	windows11-64-24h2-shippable	bytecode-cached cold fission webrender	76.27 -> 84.03	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 44707

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 1728111

Comment 2

[Benjamin VanderSloot [:bvandersloot]]

This shim is loading before FCP. We should probably disable it on Bing as the graceful degradation of the website without the shim is better than this regression. I'll do this.

Comment 3

[Benjamin VanderSloot [:bvandersloot]]

Attachment: Bug 1960866 - Disable account icon shim on Bing because of perf regression - r=twisniewski!

Comment 4

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

Set release status flags based on info from the regressing bug 1728111

Comment 5

[Ryan VanderMeulen [:RyanVM]]

Hi Tom, can we get this reviewed soon? Next week is the final week of beta for Fx139 assuming we want to address this regression in time for that.

Comment 6

[Thomas Wisniewski [:twisniewski]]

Yes, sorry for the delay here. I'll r+ this soon and commandeer it to drop the version-number change so I can land it today or tomorrow.

Comment 7

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/a34b41af73c6
Disable account icon shim on Bing because of perf regression - r=twisniewski,webcompat-reviewers

Comment 8

[Cosmin Sabou [:CosminS]]

https://hg.mozilla.org/mozilla-central/rev/a34b41af73c6

Comment 9

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

The patch landed in nightly and beta is affected.
:bvandersloot, is this bug important enough to require an uplift?

• If yes, please nominate the patch for beta approval.
  • See https://wiki.mozilla.org/Release_Management/Requesting_an_Uplift for documentation on how to request an uplift.
• If no, please set status-firefox139 to wontfix.

For more information, please visit BugBot documentation.

Comment 10

[Benjamin VanderSloot [:bvandersloot]]

I think we should Beta Uplift. Tom, have you done this for a shim before?

Comment 11

[Thomas Wisniewski [:twisniewski]]

Attachment: Bug 1960866 - Disable account icon shim on Bing because of perf regression

Comment 12

[Thomas Wisniewski [:twisniewski]]

Comment on attachment 9486344 [details]
Bug 1960866 - Disable account icon shim on Bing because of perf regression

Beta/Release Uplift Approval Request

• User impact if declined/Reason for urgency: Users may experience performance issues on Bing
• Is this code covered by automated tests?: No
• Has the fix been verified in Nightly?: Yes
• Needs manual test from QE?: No
• If yes, steps to reproduce:
• List of other uplifts needed: None
• Risk to taking this patch: Low
• Why is the change risky/not risky? (and alternatives if risky): This only affects Bing, and only requires a trivial change to our webcompat addon.
• String changes made/needed: none
• Is Android affected?: Yes

Comment 13

[Pulsebot]

https://hg.mozilla.org/releases/mozilla-beta/rev/6559f43a0b5d