Bug: 93.03 - 37.73% welcome loadtime / welcome fcp + 9 more (OSX, Windows) regression on Tue Nov 07 2023
Status: RESOLVED
Priority: P1
Resolution: FIXED
Created: 2023-11-10 15:31:38+00:00
Resolved: 2023-12-07 18:23:45+00:00

Perfherder has detected a browsertime performance regression from push [0bda9015bace079f555c7ad49ffe196459218ee0](https://hg.mozilla.org/integration/autoland/pushloghtml?changeset=0bda9015bace079f555c7ad49ffe196459218ee0). As author of one of the patches included in that push, we need your help to address this regression.

== Change summary for alert #40149 (as of Tue, 07 Nov 2023 14:18:31 GMT) ==

### Regressions:

| **Ratio** | **Test** | **Platform** | **Options** | **Absolute values (old vs new)** |  **Performance Profiles** | 
|--|--|--|--|--|--| 
| [93%](https://treeherder.mozilla.org/perfherder/graphs?timerange=1209600&series=autoland,3937067,1,13)  | [welcome](https://firefox-source-docs.mozilla.org/testing/perfdocs/raptor.html#welcome-c) loadtime | linux1804-64-shippable-qr | cold fission webrender | 72.64 -> 140.27 | [Before](https://profiler.firefox.com/from-url/https%3A%2F%2Ffirefox-ci-tc.services.mozilla.com%2Fapi%2Fqueue%2Fv1%2Ftask%2FGJhrjMpAQMGOzYiPpkkWIQ%2Fruns%2F0%2Fartifacts%2Fpublic%2Ftest_info%2Fprofile_welcome.zip)/[After](https://profiler.firefox.com/from-url/https%3A%2F%2Ffirefox-ci-tc.services.mozilla.com%2Fapi%2Fqueue%2Fv1%2Ftask%2FRW4fbBVHRd-Y1u4FvnfDdw%2Fruns%2F0%2Fartifacts%2Fpublic%2Ftest_info%2Fprofile_welcome.zip) |
| [84%](https://treeherder.mozilla.org/perfherder/graphs?timerange=1209600&series=autoland,3913743,1,13)  | [welcome](https://firefox-source-docs.mozilla.org/testing/perfdocs/raptor.html#welcome-c) loadtime | windows10-64-shippable-qr | cold fission webrender | 53.49 -> 98.22 | [Before](https://profiler.firefox.com/from-url/https%3A%2F%2Ffirefox-ci-tc.services.mozilla.com%2Fapi%2Fqueue%2Fv1%2Ftask%2FCbCLQ4BPT4-9svOHdzwXaQ%2Fruns%2F0%2Fartifacts%2Fpublic%2Ftest_info%2Fprofile_welcome.zip)/[After](https://profiler.firefox.com/from-url/https%3A%2F%2Ffirefox-ci-tc.services.mozilla.com%2Fapi%2Fqueue%2Fv1%2Ftask%2FPZo0nXjZSZONzl6slYnIqw%2Fruns%2F0%2Fartifacts%2Fpublic%2Ftest_info%2Fprofile_welcome.zip) |
| [59%](https://treeherder.mozilla.org/perfherder/graphs?timerange=1209600&series=autoland,3937071,1,13)  | [welcome](https://firefox-source-docs.mozilla.org/testing/perfdocs/raptor.html#welcome-c) loadtime | linux1804-64-shippable-qr | fission warm webrender | 44.90 -> 71.48 | [Before](https://profiler.firefox.com/from-url/https%3A%2F%2Ffirefox-ci-tc.services.mozilla.com%2Fapi%2Fqueue%2Fv1%2Ftask%2FGJhrjMpAQMGOzYiPpkkWIQ%2Fruns%2F0%2Fartifacts%2Fpublic%2Ftest_info%2Fprofile_welcome.zip)/[After](https://profiler.firefox.com/from-url/https%3A%2F%2Ffirefox-ci-tc.services.mozilla.com%2Fapi%2Fqueue%2Fv1%2Ftask%2FRW4fbBVHRd-Y1u4FvnfDdw%2Fruns%2F0%2Fartifacts%2Fpublic%2Ftest_info%2Fprofile_welcome.zip) |
| [58%](https://treeherder.mozilla.org/perfherder/graphs?timerange=1209600&series=autoland,3932989,1,13)  | [welcome](https://firefox-source-docs.mozilla.org/testing/perfdocs/raptor.html#welcome-c) loadtime | macosx1015-64-shippable-qr | fission warm webrender | 28.36 -> 44.86 | [Before](https://profiler.firefox.com/from-url/https%3A%2F%2Ffirefox-ci-tc.services.mozilla.com%2Fapi%2Fqueue%2Fv1%2Ftask%2FOgs1_9nuRw6z1zMEi2fksQ%2Fruns%2F0%2Fartifacts%2Fpublic%2Ftest_info%2Fprofile_welcome.zip)/[After](https://profiler.firefox.com/from-url/https%3A%2F%2Ffirefox-ci-tc.services.mozilla.com%2Fapi%2Fqueue%2Fv1%2Ftask%2FP8Gq9dF0RFqiAf1OmbcAVA%2Fruns%2F0%2Fartifacts%2Fpublic%2Ftest_info%2Fprofile_welcome.zip) |
| [38%](https://treeherder.mozilla.org/perfherder/graphs?timerange=1209600&series=autoland,3913747,1,13)  | [welcome](https://firefox-source-docs.mozilla.org/testing/perfdocs/raptor.html#welcome-c) loadtime | windows10-64-shippable-qr | fission warm webrender | 32.88 -> 45.29 | [Before](https://profiler.firefox.com/from-url/https%3A%2F%2Ffirefox-ci-tc.services.mozilla.com%2Fapi%2Fqueue%2Fv1%2Ftask%2FCbCLQ4BPT4-9svOHdzwXaQ%2Fruns%2F0%2Fartifacts%2Fpublic%2Ftest_info%2Fprofile_welcome.zip)/[After](https://profiler.firefox.com/from-url/https%3A%2F%2Ffirefox-ci-tc.services.mozilla.com%2Fapi%2Fqueue%2Fv1%2Ftask%2FPZo0nXjZSZONzl6slYnIqw%2Fruns%2F0%2Fartifacts%2Fpublic%2Ftest_info%2Fprofile_welcome.zip) |
| [32%](https://treeherder.mozilla.org/perfherder/graphs?timerange=1209600&series=autoland,3913745,1,13)  | [welcome](https://firefox-source-docs.mozilla.org/testing/perfdocs/raptor.html#welcome-c) fcp | windows10-64-shippable-qr | fission warm webrender | 39.98 -> 52.85 | [Before](https://profiler.firefox.com/from-url/https%3A%2F%2Ffirefox-ci-tc.services.mozilla.com%2Fapi%2Fqueue%2Fv1%2Ftask%2FCbCLQ4BPT4-9svOHdzwXaQ%2Fruns%2F0%2Fartifacts%2Fpublic%2Ftest_info%2Fprofile_welcome.zip)/[After](https://profiler.firefox.com/from-url/https%3A%2F%2Ffirefox-ci-tc.services.mozilla.com%2Fapi%2Fqueue%2Fv1%2Ftask%2FPZo0nXjZSZONzl6slYnIqw%2Fruns%2F0%2Fartifacts%2Fpublic%2Ftest_info%2Fprofile_welcome.zip) |
| [11%](https://treeherder.mozilla.org/perfherder/graphs?timerange=1209600&series=autoland,3913741,1,13)  | [welcome](https://firefox-source-docs.mozilla.org/testing/perfdocs/raptor.html#welcome-c) fcp | windows10-64-shippable-qr | cold fission webrender | 80.44 -> 88.90 | [Before](https://profiler.firefox.com/from-url/https%3A%2F%2Ffirefox-ci-tc.services.mozilla.com%2Fapi%2Fqueue%2Fv1%2Ftask%2FCbCLQ4BPT4-9svOHdzwXaQ%2Fruns%2F0%2Fartifacts%2Fpublic%2Ftest_info%2Fprofile_welcome.zip)/[After](https://profiler.firefox.com/from-url/https%3A%2F%2Ffirefox-ci-tc.services.mozilla.com%2Fapi%2Fqueue%2Fv1%2Ftask%2FPZo0nXjZSZONzl6slYnIqw%2Fruns%2F0%2Fartifacts%2Fpublic%2Ftest_info%2Fprofile_welcome.zip) |
| [2%](https://treeherder.mozilla.org/perfherder/graphs?timerange=1209600&series=autoland,3937756,1,13)  | [welcome](https://firefox-source-docs.mozilla.org/testing/perfdocs/raptor.html#welcome-c) ContentfulSpeedIndex | linux1804-64-shippable-qr | cold fission webrender | 1,195.23 -> 1,224.41 | [Before](https://profiler.firefox.com/from-url/https%3A%2F%2Ffirefox-ci-tc.services.mozilla.com%2Fapi%2Fqueue%2Fv1%2Ftask%2FGJhrjMpAQMGOzYiPpkkWIQ%2Fruns%2F0%2Fartifacts%2Fpublic%2Ftest_info%2Fprofile_welcome.zip)/[After](https://profiler.firefox.com/from-url/https%3A%2F%2Ffirefox-ci-tc.services.mozilla.com%2Fapi%2Fqueue%2Fv1%2Ftask%2FRW4fbBVHRd-Y1u4FvnfDdw%2Fruns%2F0%2Fartifacts%2Fpublic%2Ftest_info%2Fprofile_welcome.zip) |
| [2%](https://treeherder.mozilla.org/perfherder/graphs?timerange=1209600&series=autoland,3937758,1,13)  | [welcome](https://firefox-source-docs.mozilla.org/testing/perfdocs/raptor.html#welcome-c) PerceptualSpeedIndex | linux1804-64-shippable-qr | cold fission webrender | [1,197.07](https://firefox-ci-tc.services.mozilla.com/api/queue/v1/task/GJhrjMpAQMGOzYiPpkkWIQ/runs/0/artifacts/public/test_info/browsertime-results.tgz) -> [1,221.73](https://firefox-ci-tc.services.mozilla.com/api/queue/v1/task/RW4fbBVHRd-Y1u4FvnfDdw/runs/0/artifacts/public/test_info/browsertime-results.tgz) | [Before](https://profiler.firefox.com/from-url/https%3A%2F%2Ffirefox-ci-tc.services.mozilla.com%2Fapi%2Fqueue%2Fv1%2Ftask%2FGJhrjMpAQMGOzYiPpkkWIQ%2Fruns%2F0%2Fartifacts%2Fpublic%2Ftest_info%2Fprofile_welcome.zip)/[After](https://profiler.firefox.com/from-url/https%3A%2F%2Ffirefox-ci-tc.services.mozilla.com%2Fapi%2Fqueue%2Fv1%2Ftask%2FRW4fbBVHRd-Y1u4FvnfDdw%2Fruns%2F0%2Fartifacts%2Fpublic%2Ftest_info%2Fprofile_welcome.zip) |
| [2%](https://treeherder.mozilla.org/perfherder/graphs?timerange=1209600&series=autoland,3937753,1,13)  | [welcome](https://firefox-source-docs.mozilla.org/testing/perfdocs/raptor.html#welcome-c) SpeedIndex | linux1804-64-shippable-qr | cold fission webrender | [1,194.73](https://firefox-ci-tc.services.mozilla.com/api/queue/v1/task/GJhrjMpAQMGOzYiPpkkWIQ/runs/0/artifacts/public/test_info/browsertime-results.tgz) -> [1,218.82](https://firefox-ci-tc.services.mozilla.com/api/queue/v1/task/RW4fbBVHRd-Y1u4FvnfDdw/runs/0/artifacts/public/test_info/browsertime-results.tgz) | [Before](https://profiler.firefox.com/from-url/https%3A%2F%2Ffirefox-ci-tc.services.mozilla.com%2Fapi%2Fqueue%2Fv1%2Ftask%2FGJhrjMpAQMGOzYiPpkkWIQ%2Fruns%2F0%2Fartifacts%2Fpublic%2Ftest_info%2Fprofile_welcome.zip)/[After](https://profiler.firefox.com/from-url/https%3A%2F%2Ffirefox-ci-tc.services.mozilla.com%2Fapi%2Fqueue%2Fv1%2Ftask%2FRW4fbBVHRd-Y1u4FvnfDdw%2Fruns%2F0%2Fartifacts%2Fpublic%2Ftest_info%2Fprofile_welcome.zip) |
| [2%](https://treeherder.mozilla.org/perfherder/graphs?timerange=1209600&series=autoland,3937754,1,13)  | [welcome](https://firefox-source-docs.mozilla.org/testing/perfdocs/raptor.html#welcome-c) FirstVisualChange | linux1804-64-shippable-qr | cold fission webrender | [1,157.48](https://firefox-ci-tc.services.mozilla.com/api/queue/v1/task/GJhrjMpAQMGOzYiPpkkWIQ/runs/0/artifacts/public/test_info/browsertime-results.tgz) -> [1,180.73](https://firefox-ci-tc.services.mozilla.com/api/queue/v1/task/RW4fbBVHRd-Y1u4FvnfDdw/runs/0/artifacts/public/test_info/browsertime-results.tgz) | [Before](https://profiler.firefox.com/from-url/https%3A%2F%2Ffirefox-ci-tc.services.mozilla.com%2Fapi%2Fqueue%2Fv1%2Ftask%2FGJhrjMpAQMGOzYiPpkkWIQ%2Fruns%2F0%2Fartifacts%2Fpublic%2Ftest_info%2Fprofile_welcome.zip)/[After](https://profiler.firefox.com/from-url/https%3A%2F%2Ffirefox-ci-tc.services.mozilla.com%2Fapi%2Fqueue%2Fv1%2Ftask%2FRW4fbBVHRd-Y1u4FvnfDdw%2Fruns%2F0%2Fartifacts%2Fpublic%2Ftest_info%2Fprofile_welcome.zip) |
### Improvements:

| **Ratio** | **Test** | **Platform** | **Options** | **Absolute values (old vs new)** |  **Performance Profiles** | 
|--|--|--|--|--|--| 
| [9%](https://treeherder.mozilla.org/perfherder/graphs?timerange=1209600&series=autoland,3937069,1,13)  | [welcome](https://firefox-source-docs.mozilla.org/testing/perfdocs/raptor.html#welcome-c) fcp | linux1804-64-shippable-qr | fission warm webrender | 59.07 -> 53.99 | [Before](https://profiler.firefox.com/from-url/https%3A%2F%2Ffirefox-ci-tc.services.mozilla.com%2Fapi%2Fqueue%2Fv1%2Ftask%2FGJhrjMpAQMGOzYiPpkkWIQ%2Fruns%2F0%2Fartifacts%2Fpublic%2Ftest_info%2Fprofile_welcome.zip)/[After](https://profiler.firefox.com/from-url/https%3A%2F%2Ffirefox-ci-tc.services.mozilla.com%2Fapi%2Fqueue%2Fv1%2Ftask%2FRW4fbBVHRd-Y1u4FvnfDdw%2Fruns%2F0%2Fartifacts%2Fpublic%2Ftest_info%2Fprofile_welcome.zip) |
| [6%](https://treeherder.mozilla.org/perfherder/graphs?timerange=1209600&series=autoland,3937065,1,13)  | [welcome](https://firefox-source-docs.mozilla.org/testing/perfdocs/raptor.html#welcome-c) fcp | linux1804-64-shippable-qr | cold fission webrender | 130.94 -> 122.95 | [Before](https://profiler.firefox.com/from-url/https%3A%2F%2Ffirefox-ci-tc.services.mozilla.com%2Fapi%2Fqueue%2Fv1%2Ftask%2FGJhrjMpAQMGOzYiPpkkWIQ%2Fruns%2F0%2Fartifacts%2Fpublic%2Ftest_info%2Fprofile_welcome.zip)/[After](https://profiler.firefox.com/from-url/https%3A%2F%2Ffirefox-ci-tc.services.mozilla.com%2Fapi%2Fqueue%2Fv1%2Ftask%2FRW4fbBVHRd-Y1u4FvnfDdw%2Fruns%2F0%2Fartifacts%2Fpublic%2Ftest_info%2Fprofile_welcome.zip) |

For up to date results, see: https://treeherder.mozilla.org/perfherder/alerts?id=40149

Details of the alert can be found in the [alert summary](https://treeherder.mozilla.org/perfherder/alerts?id=40003), including links to graphs and comparisons for each of the affected tests. Please follow our [guide to handling regression bugs](https://wiki.mozilla.org/TestEngineering/Performance/Handling_regression_bugs) and **let us know your plans within 3 business days, or the patch(es) may be backed out** in accordance with our [regression policy](https://www.mozilla.org/en-US/about/governance/policies/regressions/).

 If you need the profiling jobs you can trigger them yourself from treeherder job view or ask a sheriff to do that for you.

For more information on performance sheriffing please see our [FAQ](https://wiki.mozilla.org/TestEngineering/Performance/FAQ).