Closed Bug 1631520 Opened 4 years ago Closed 4 years ago

Developer tools inspector is very slow on YouTube

Categories

(DevTools :: Inspector, defect)

Product:
DevTools
Component:
Inspector
Version:
75 Branch
Type:
defect
Priority:
Not set
Severity:
normal

Tracking

(Performance Impact:medium)

Status:
RESOLVED DUPLICATE of bug 1623988
Project Flags:
Performance Impact medium

People

(Reporter: gwarser, Unassigned)

References

Details

User Agent: Mozilla/5.0 (X11; Linux x86_64; rv:77.0) Gecko/20100101 Firefox/77.0

Steps to reproduce:

Open YouTube, right click and select "Inspect element" and then try scrolling.

Actual results:

Few seconds long lags.

https://perfht.ml/34RXqTZ

A lot of the time in here is spent inside hasCSSVariable, this work is being done deep inside DevTools. Based on that I am changing the component. Still marking this as qf:p2 as we believe it can have a significant impact on the user experience for using our developer tools and we want to keep this on the perf team watchlist.

Component: Performance → Inspector
Product: Core → DevTools
Whiteboard: [qf:p2]
See Also: → 1623988

This has the same root cause as bug 1623988 (very large number of CSS variables which need to be resolved and show in the Rules panel). Marking as a duplicate. I copied over the "qf:p2" whiteboard label.

I'm working on a patch for that bug which will alleviate the performance hit for YouTube as well.

Status: UNCONFIRMED → RESOLVED
Closed: 4 years ago
Resolution: --- → DUPLICATE
Performance Impact: --- → P2
Whiteboard: [qf:p2]
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