helpdeskgeek site runs a lot more JS in Firefox than in Chrome (checkerboards during scrolling)
Categories
(Core :: Performance, defect)
Tracking
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| Performance Impact | high |
People
(Reporter: mstange, Unassigned)
Details
(Keywords: perf:responsiveness, reproducible)
Steps to reproduce:
- Go to https://helpdeskgeek.com/how-to/how-to-type-letters-with-accents-on-windows-mac-and-linux/
- Scroll down.
- Scroll up.
Expected results:
The page should be responsive.
Actual results:
Lots of checkerboarding, text selection is unresponsive for multiple seconds.
Profile: https://share.firefox.dev/43zRpcT
The page seems to be poorly written but works fine in Chrome.
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Comment 1•8 months ago
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The Performance Impact Calculator has determined this bug's performance impact to be high. If you'd like to request re-triage, you can reset the Performance Impact flag to "?" or needinfo the triage sheriff.
Platforms: [x] Windows [x] macOS [x] Linux
Impact on browser: Causes noticeable jank
[x] Able to reproduce locally
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Comment 2•8 months ago
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:ksenia, this site seems to be using old DOM mutation events and is thrashing, but doesn't seem to affect android or chrome and it's unclear why - would you know?
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Updated•7 months ago
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Comment 4•7 months ago
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Yeah, they're using DOMSubtreeModified listener, and a handler function is recursively adding and removing fixed class, so there it ends up in an endless loop. Mutation events been deprecated for a long time, and MutationObserver should be used instead.
Chrome handles it more gracefully, but they're removing support for it in version 127.
This would be a dupe of bug1881922
Description
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