I'd really like to use the Firefox browser (currently using Iridium), but I'm seeing a strange behavior where it "stalls" intermittently. The rendering engine seems to randomly pause activity (i.e. not responsive to scrolling input), and these pauses can last for several seconds. It also appears to affect video playback.
I haven't knowingly done anything with my user settings that would cause this to happen; I have a few add-ons, but they should all be well-behaved (1PasswordX, Facebook Container, Multi-account Container, uBlock Origin).
Has anyone seen this and figured out a solution? First, check if those are not add-ons by running a clean profile. Mere belief that they’re not the culprit is not evidence.
If the behaviour continues in a clean profile, check load during those stalls — e.g. in `htop`, which shows a nice load graph. Possibly programs Firefox downloads and runs (aka JavaScript) are eating all your CPU resources. If that doesn’t explain the problem, check if dmesg contains any errors that correlate with your issue. That’s unlikely, but not impossible. Also see if you do have enough of RAM and no swapping occurs. That shouldn’t be a concern on any modern computer, but the symptom is similar and, since I have no specific ideas, everything’s worth checking.