Anyone else have this issue? I thought maybe it was just my shitty surface pro 3 but it happens on my T530, T460s, and my desktop. I thought maybe it was an extension I had so I uninstalled them all except ublock. Still happening. For now I've just switched to librewolf and installed all the extensions I had on Firefox. Works fine and doesn't keep my CPU at 100% so problem solved I guess, but I'm still curious if anyone else has this issue?
Create a new Firefox profile, set it as default, then restart Firefox and see if the problem still persists.
I get this sporadically, probably once a week on average. Most of the time it seems to be caused by a specific tab and resolves itself after closing the tab (in my case Slack is the most common culprit).
Sounds like a serious bug. What's the distro and package format? It might be a single package issue.
I recently experienced something similar on one of my PCs with an nvidia card (running Fedora Atomic) - turns out it was weirdness with wayland and switching to x11 made it go away.
Please add the version of Firefox to the post so others can be better informed
Whenever you have issue with Firefox, first thing that you should try is 'Troubleshoot mode' -
Firefox Menu > Help > Troubleshoot Mode