Bug: 3.26 - 2.51% google-slides fcp / google-slides fcp (Windows) regression on Wed April 6 2022
Status: RESOLVED
Priority: --
Resolution: WORKSFORME
Created: 2022-04-15 16:41:41+00:00
Resolved: 2022-04-20 01:28:27+00:00

Perfherder has detected a browsertime performance regression from push [848cac0abe46c6af79afee04a31eeee6cf07eaee](https://hg.mozilla.org/integration/autoland/pushloghtml?changeset=848cac0abe46c6af79afee04a31eeee6cf07eaee). 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)**| 
|--|--|--|--|--| 
| 3% | [google-slides](https://firefox-source-docs.mozilla.org/testing/perfdocs/raptor.html#google-slides-d) fcp | windows10-64-shippable-qr | fission warm webrender | 216.08 -> 223.12 |
| 3% | [google-slides](https://firefox-source-docs.mozilla.org/testing/perfdocs/raptor.html#google-slides-d) fcp | windows10-64-shippable-qr | fission warm webrender | [215.88](https://firefox-ci-tc.services.mozilla.com/api/queue/v1/task/JffBza-ZSqqX9PRzEqj9EQ/runs/0/artifacts/public/test_info/browsertime-results.tgz) -> [221.29](https://firefox-ci-tc.services.mozilla.com/api/queue/v1/task/N9RHfLvbRHGp5A3SI01yCA/runs/0/artifacts/public/test_info/browsertime-results.tgz) |
### Improvements:

| **Ratio** | **Test** | **Platform** | **Options** | **Absolute values (old vs new)**| 
|--|--|--|--|--| 
| 29% | [linkedin](https://firefox-source-docs.mozilla.org/testing/perfdocs/raptor.html#linkedin-d) dcf | windows10-64-shippable-qr | cold fission webrender | 1,779.71 -> 1,268.79 |
| 27% | [linkedin](https://firefox-source-docs.mozilla.org/testing/perfdocs/raptor.html#linkedin-d) dcf | linux1804-64-shippable-qr | cold fission webrender | 1,797.88 -> 1,320.46 |
| 25% | [linkedin](https://firefox-source-docs.mozilla.org/testing/perfdocs/raptor.html#linkedin-d) dcf | linux1804-64-shippable-qr | cold fission webrender | 1,777.15 -> 1,326.50 |
| 10% | [twitch](https://firefox-source-docs.mozilla.org/testing/perfdocs/raptor.html#twitch-d) SpeedIndex | linux1804-64-shippable-qr | fission warm webrender | 487.17 -> 436.83 |
| 9% | [buzzfeed](https://firefox-source-docs.mozilla.org/testing/perfdocs/raptor.html#buzzfeed-d) dcf | windows10-64-shippable-qr | fission warm webrender | 545.12 -> 494.96 |
|...|...|...|...|...|
| 3% | [bing](https://firefox-source-docs.mozilla.org/testing/perfdocs/raptor.html#bing-m) SpeedIndex | android-hw-g5-7-0-arm7-shippable-qr | warm webrender | 719.38 -> 698.75 |


Details of the alert can be found in the [alert summary](https://treeherder.mozilla.org/perfherder/alerts?id=33794), 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).