UI freezes for multiple seconds

[germain-gg]

Steps to reproduce

Haven't managed to consistently reproduce the issue.
Also experienced by @novocaine and @turt2live today

Outcome

What did you expect?

A smooth 60fps rendering

What happened instead?

UI is frozen for multiple seconds

Operating system

No response

Browser information

No response

URL for webapp

No response

Application version

No response

Homeserver

No response

Will you send logs?

No

[andybalaam]

I just saw my UI freeze and I had to refresh to get back to a usable system.
Ubuntu 21.10
Firefox 64.0
https://develop.element.io
It happened when I entered the Dendrite room.

[andybalaam]

This just happened to me again. I'll keep the tab around in case I can debug or something.

[andybalaam]

I opened a new tab on develop.element.io and it immediately froze too, which might be a helpful data point?

[dbkr]

Repro steps:

1. join the dendrite room (https://matrix.to/#/#dendrite:matrix.org)
2. switch to a different room
3. clear cache & reload
4. switch to the dendrite room
5. freeze

and, hopefully irrelevant now we have a fix, but I nabbed a profile anyway: