https://bugzilla.mozilla.org/show_bug.cgi?id=1600698 and https://bugzilla.mozilla.org/show_bug.cgi?id=1606823 document the performance issues. Mozilla is working on the issue, but its not yet resolved.
Re:Jitsi Meet features update
by DenseComet on Wednesday April 08, 2020 @02:01PM
(#22815344)
There are known issues with Firefox clients causing deteriorated quality for all users. They're working on it, but current workarounds are use Chromium, a chromium based browser, or the desktop app.
This is not true, the whole conference performs significantly worse at much higher bandwidth usage if there is a Firefox client, due to implementation limitations.
In other words, your experience might be good with Firefox, but it's worse for the others.
I am using it on firefox and it works anyway, but now my mom is being forced to use it for work and she's asking whether there are any problems (there aren't).
they should just take it away already, it's working well anyway.