Firefox

I'd start by disabling the plugins one by one or a couple at a time to see if any of them might be the culprit

Oh man. Many, MANY years ago I had what certainty looks like an identical problem. I actually jumped so for several years because I couldn't stand it any longer and no one could help me. I'm trying to remember what I finally did that solved it, and I'm about 95% sure I had to create a brand new, clean profile. Just reinstalling or refreshing firefox did not do the trick, I had to make a new profile. It was so long ago that I have zero recollection of how to do even that anymore, but if I were you, I'd give it a shot .

Unfortunately this is 100% an issue with your system and not Firefox.

Edit: sorry if that reply wasn't helpful. Just calling it out to prevent the inevitable comments blaming Firefox itself lol.

Have you tried a fresh profile? If you have the same issues as before then it sounds like you're running your old one too. And it could also be a single one of those add-ons bring the issue, so try figure that out too if the fresh profile doesn't do the trick.

I recently spilled water on my mouse. Everything seemed fine, but ff kept hanging more or less as you describe. Swapped out the mouse and it was fine.

Probably isn't your problem, just thought I'd let you know.

This reeks of a problem with your system, not Firefox.

Are you using an HDD or SDD?

I would disable any custom fonts you have added to Windows too. Or at least check them for font conflicts. And check the reliability reporter to see if it says anything in particular about the days when FF crashes.

EDIT: I also just noticed you have a VPN in your plugins. The Firefox VPN used to behave pretty wonkily if it got a bad connection and could look like everything was frozen. This would be my immediate prime suspect if you think it’s extensions.

I also agree a fresh profile is a huge pain but worth a shot if all else fails. It can make a difference when you can’t trace down what about:config you boned horribly haha.

I'd run a memory test overnight.

Can you try using a tool like Crystal disk to check your drive health. Once when I had similar symptoms my drive was just weeks from failing completely.

Firefox (in my experience) does seem to lag on some devices especially ones that run older hardware. I have a really old Windows 7 laptop tucked away somewhere that had both Firefox and Chrome installed.

While Chrome runs like a hot knife through butter, I can't say the same about Firefox. I popped open a Windows 8 VM as well and Firefox still seems to run smoothly on that. On my relatively newer laptop, Firefox runs like a breeze.

One of the main culprits might be your hardware (most likely RAM) or your OS. If the above 2 aren't the issue, then I'd suggest making a new profile with no modifications and see how that runs. If that doesn't work then try using the Firefox Extended Support Release. It's known to be more stable and less frequent to crashes.

Works fine on my Mac and Linux machines. Maybe this is a Windows issue.

Not a debugging help, but: I have the same issues. Especially the tab thing. Open one, try to open a page, nothing happens. This is especially bad on android for me.

Number 3 is something Firefox has done for ages, even before quantum. It will refuse to start of there is another, non-responding, instance running. I think they actually added a dialog for it that sometimes works.

Number 1 is something I see on Linux every now and then. For me, only the mouse input is ignored then. But sometimes Firefox just hangs without crashing (Probably some loop somewhere went nuts).

I do not have solutions for this. I just want to add, that it probably is not because of OPs system.

Downloaded installer or MSStore? I had an issue for a short time (a single version then it got fixed) where only the Store version caused system stuttering.

Also maybe, you haven't messed with Windows virtual memory page sizing?

You could try a VM with just Firefox to see if there's another program interfering with it?

Do you get any other issues on your pc not related to firefox

Also note down the times the issues occur and look at the event viewer in Windows and look at the times you've noted down to see if you can see anything odd

The ideal way to troubleshoot is to get as much information as you can about the issue before you begin troubleshooting steps

Can you reproduce the issue with no extensions running?

Can you reproduce the issue on a different machine?

Try to isolate the variables that are causing the issue.

Vanilla Firefox with no modifications, no extensions, nothing, does it reproduce the issue?

I'm not encountering issues like you're describing, so I think it's something specific to your environment

Are you running this on the same PC/OS install that you were having problems on previously?

Something that may help with diagnosis is to try a portable version of firefox. If the portable version works properly and your installed version does not then it could be either some setting or library that is having problems.

Would also try running as a different user to see if maybe the issue is with something in your user profile.