Bug: 73.17 - 12.38% welcome ContentfulSpeedIndex / welcome ContentfulSpeedIndex + 4 more (Linux, OSX, Windows) regression on Fri April 1 2022
Status: RESOLVED
Priority: P1
Resolution: FIXED
Created: 2022-04-07 16:54:36+00:00
Resolved: 2022-05-04 18:46:36+00:00

Perfherder has detected a browsertime performance regression from push [53e6fbe77dff1c74b11e1903ccf3084a39f90cd0](https://hg.mozilla.org/integration/autoland/pushloghtml?changeset=53e6fbe77dff1c74b11e1903ccf3084a39f90cd0). As author of one of the patches included in that push, we need your help to address this regression.

### Regressions:

| **Ratio** | **Test** | **Platform** | **Options** | **Absolute values (old vs new)**| 
|--|--|--|--|--| 
| 73% | [welcome](https://firefox-source-docs.mozilla.org/testing/perfdocs/raptor.html#welcome-c) ContentfulSpeedIndex | windows10-64-shippable-qr | fission warm webrender | 324.83 -> 562.50 |
| 52% | [welcome](https://firefox-source-docs.mozilla.org/testing/perfdocs/raptor.html#welcome-c) ContentfulSpeedIndex | windows10-64-shippable-qr | fission warm webrender | 354.92 -> 538.33 |
| 24% | [welcome](https://firefox-source-docs.mozilla.org/testing/perfdocs/raptor.html#welcome-c) ContentfulSpeedIndex | macosx1015-64-shippable-qr | fission warm webrender | 1,366.33 -> 1,693.25 |
| 20% | [welcome](https://firefox-source-docs.mozilla.org/testing/perfdocs/raptor.html#welcome-c) ContentfulSpeedIndex | linux1804-64-shippable-qr | fission warm webrender | 1,338.17 -> 1,601.42 |
| 12% | [welcome](https://firefox-source-docs.mozilla.org/testing/perfdocs/raptor.html#welcome-c) ContentfulSpeedIndex | macosx1015-64-shippable-qr | cold fission webrender | 1,594.42 -> 1,793.08 |
| 12% | [welcome](https://firefox-source-docs.mozilla.org/testing/perfdocs/raptor.html#welcome-c) ContentfulSpeedIndex | linux1804-64-shippable-qr | cold fission webrender | 1,500.92 -> 1,686.67 |
### Improvements:

| **Ratio** | **Test** | **Platform** | **Options** | **Absolute values (old vs new)**| 
|--|--|--|--|--| 
| 28% | [welcome](https://firefox-source-docs.mozilla.org/testing/perfdocs/raptor.html#welcome-c) PerceptualSpeedIndex | windows10-64-shippable-qr | fission warm webrender | 281.58 -> 204.00 |
| 26% | [welcome](https://firefox-source-docs.mozilla.org/testing/perfdocs/raptor.html#welcome-c) PerceptualSpeedIndex | windows10-64-shippable-qr | cold fission webrender | 380.25 -> 281.83 |
| 20% | [welcome](https://firefox-source-docs.mozilla.org/testing/perfdocs/raptor.html#welcome-c) SpeedIndex | windows10-64-shippable-qr | cold fission webrender | 272.83 -> 217.17 |
| 15% | [welcome](https://firefox-source-docs.mozilla.org/testing/perfdocs/raptor.html#welcome-c) fcp | macosx1015-64-shippable-qr | cold fission webrender | 108.92 -> 92.29 |
| 8% | [welcome](https://firefox-source-docs.mozilla.org/testing/perfdocs/raptor.html#welcome-c) PerceptualSpeedIndex | macosx1015-64-shippable-qr | cold fission webrender | 1,503.96 -> 1,380.17 |
|...|...|...|...|...|
| 5% | [welcome](https://firefox-source-docs.mozilla.org/testing/perfdocs/raptor.html#welcome-c) PerceptualSpeedIndex | macosx1015-64-shippable-qr | fission warm webrender | 1,388.00 -> 1,314.25 |


Details of the alert can be found in the [alert summary](https://treeherder.mozilla.org/perfherder/alerts?id=33737), 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 offending patch(es) will be backed out** in accordance with our [regression policy](https://www.mozilla.org/en-US/about/governance/policies/regressions/).

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