Bugzilla

**Affected versions**
* 81.0a1 (2020-08-12) 

**Affected platforms**
* Windows 10, Ubuntu 18;

**Steps to reproduce**
1. Launch Firefox;
2. Set the browser over half the screen so @media-querries affect the page-resize;
3. Access [this link](https://www.intersport.ro/barbati/incaltaminte-barbati/colectia-noua-pantofi-barbati/nike-kyrie-flytrap-iii_642122/);
4. Click on the carousel to swap between images;

**Expected result**
* carousel goes smooth;

**Actual result**
* swapping images is laggy;

**Regression range**
* recent regression, will check and provide one asap;

**Additional notes**
* attached screenshot with the issue;
* macOS 11.0 appears to work fine;
* suggested severity is S3, since it yelds a poor UX on the site.

**Affected versions**
* 81.0a1 (2020-08-12) 

**Affected platforms**
* Windows 10, Ubuntu 18;

**Steps to reproduce**
1. Launch Firefox;
2. Set the browser over half the screen so @media-querries affect the page-resize;
3. Access [this link](https://www.intersport.ro/barbati/incaltaminte-barbati/colectia-noua-pantofi-barbati/nike-kyrie-flytrap-iii_642122/);
4. Click on the carousel to swap between images;

**Expected result**
* carousel goes smooth;

**Actual result**
* swapping images is laggy;

**Regression range**
* potential regressor: 1656418;
* pushlog [URL](https://hg.mozilla.org/mozilla-central/pushloghtml?fromchange=4b30578a98809b44d7ed8bdbba264d3ed1ed8c6d&tochange=255b4f5888e9e9cdd40f59fec969af247859d76a);
* last good: 2020-08-02;
* first bad: 2020-08-03;

**Additional notes**
* attached screenshot with the issue;
* macOS 11.0 appears to work fine;
* suggested severity is S3, since it yelds a poor UX on the site.

**Affected versions**
* 81.0a1 (2020-08-12);
* 82.0a1 (2020-08-24); 

**Affected platforms**
* Windows 10, Ubuntu 18;

**Steps to reproduce**
1. Launch Firefox;
2. Set the browser over half the screen so @media-querries affect the page-resize;
3. Access [this link](https://www.intersport.ro/barbati/incaltaminte-barbati/colectia-noua-pantofi-barbati/nike-kyrie-flytrap-iii_642122/);
4. Click on the carousel to swap between images;

**Expected result**
* carousel goes smooth;

**Actual result**
* swapping images is laggy;

**Regression range**
* potential regressor: 1656418;
* pushlog [URL](https://hg.mozilla.org/mozilla-central/pushloghtml?fromchange=4b30578a98809b44d7ed8bdbba264d3ed1ed8c6d&tochange=255b4f5888e9e9cdd40f59fec969af247859d76a);
* last good: 2020-08-02;
* first bad: 2020-08-03;

**Additional notes**
* attached screenshot with the issue;
* macOS 11.0 appears to work fine;
* suggested severity is S3, since it yelds a poor UX on the site.