Description of problem: The latest version of Firefox (91.0) becomes extremely slow after that it has been started. Initially it works ok, but after a while it takes tens of seconds to response on mouse clicks. Top and iotop did not show heavy Firefox usage. See also the journal that has been attached. I'm using Firefox on GNOME Wayland, on a fully up-to-date Fedora 34. Version-Release number of selected component (if applicable): firefox-wayland.x86_64 91.0-1.fc34 How reproducible: Nearly always happens, I do not really know how long I have to wait before Firefox becomes so slow. It could be related to suspend and resume (as I use that quite often). I always have quite some tabs open (tens), but in the past hundreds of tabs worked perfectly fast. To give a raw indication, I would think that it takes several hours for Firefox to become unusable slow.
Created attachment 1816720 [details] Journal when running, stopping, and starting Firefox
It may be related to some user profile corruption so can you try to create a new profile? https://fedoraproject.org/wiki/How_to_debug_Firefox_problems?rd=Bug_info_Firefox#Test_Firefox_with_a_new_profile Also please try to open Firefox profiler when it's slow (go to profiler.firefox.com for instructions) and attach the output here. Thanks.
There's also a known bug when Firefox is slow during laggy/slow DNS response - can you check your network connection when it happens?
Hi Martin, here a pofile: https://share.firefox.dev/3BabVBf (I did not enable the data that could be identifiable to me. I you want, I can share a profile with all the details with you only.) I did not start a new user profile. I have this issue on two computers (both Fedora 34). This time it took like a day before it occurred.
OK Martin, I think I identified the site that is the root of this slowness. It is a "personal" site that is in development. I closed three tabs of it, and Firefox became responsive again. It is still the question if it should be possible that a single site can "hang" the whole of Firefox. I leave it up to you to decide whether you want to close this issue (because it is related to a "personal" project), or if you want to keep this issue open, because no site should be able to make Firefox unresponsive. Thanks for all your work on Firefox!
Hi Jan, if you have a minimal tescase it would be great to report that upstream.
I start now heavily doubting if the issue is related to the "personal" site. The problem to ascertain this is that Firefox becomes so slow that I effectively cannot check any more which sites I have open in my hundreds of tabs. But yesterday and today, I was hit by this issue again, and this time think I had the suspect "personal" site was not open. Note that it took now around five days before this occurred. I did not shutdown my computer in that time, but it suspends after 15 minutes of inactivity. I also keep Firefox always open (until I am hit by this issue). Again this happened on two different computers. I do have several extensions enabled. I will try the suggestion of creating a new profile and see if this solves the problem, and report back the results later. But this can take a while, because the issue usually only manifests after a few days of Firefox usage. And if it does not occur, I can never know for sure if it will occur again somewhere in the future.
Forgot to say: at the moment, I have two Firefox windows open on the same computer. One window functions perfectly (actually I am reporting now in that window), while the other Firefox window is hit by the issue.
A bit more details: Especially interacting with the tabs and the URL bar is extremely slow. However, it keeps working but it takes more than a minute before what I type appears in the URL bar. Switching tabs takes over 20 seconds. However, when the tab has been switched, the page is loaded, and scrolling in the page is as fast as normal, also selecting text is normal.
Maybe related to this bug: https://bugzilla.mozilla.org/show_bug.cgi?id=1728966
Simply playing a youtube stream makes the issue appear in an hour or so.
I have not seen this problem in a long time. So from my perspective this bug can be closed. I leave it open however because @udovdh recently reported seeing this issue.
I still see this issue happen. I used https://www.youtube.com/watch?v=ydYDqZQpim8 and ran FF for 2 hours or so.
When we close the tab with the livestream the rest of FF does not regain a functional state. I do have to stop/start FF.
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Fedora Linux 34 entered end-of-life (EOL) status on 2022-06-07. Fedora Linux 34 is no longer maintained, which means that it will not receive any further security or bug fix updates. As a result we are closing this bug. If you can reproduce this bug against a currently maintained version of Fedora please feel free to reopen this bug against that version. If you are unable to reopen this bug, please file a new report against the current release. Thank you for reporting this bug and we are sorry it could not be fixed.