Firefox unresponsive - loading symbol in the middle of the screen

So for a few weeks now I've had this problem come up multiple times. I notice that the browser is slowly getting more and more unresponsive while switching tabs and eventually it stops completely. I get a loading symbol in the middle of the tab, even on previously loaded ones. I can't switch tabs anymore, but I can open a new tab once per Firefox. I can open as many windows as I want, they all just show a white page and the search bar is unclickable. I don't get any error message from my computer nor Firefox. Restarting the computer (because I don't want to lose my tabs) solves the issue and it becomes perfectly responsive again, but it takes ~2 minutes to shut down, when it usually takes at most 20 seconds, because Firefox is not closing properly. I also didn't add any new add-ons before the issue started appearing. Now I wouldn't mind a restart here and there if I wasn't working as much as I do in the browser. So if anyone has an idea where to look for a solution I'd very much appreciate it.