I have this issue on two different laptops. One is a brand new HP Envy. I don't know if the issue exists even with all plugins disabled, as sometimes it takes hours for this behavior to happen, and I need to have plugins enabled to do work. A couple times a day, all tabs within the browser show a spinner. The only (useful) way to fix it is to restart the browser. If I close the browser and wait, the window disappears, but I can still see (in the windows process manager) that there are two threads running. If I wait long enough (3-5 min), firefox will crash and send a report to mozilla. To get back up faster, I can kill the threads and restart firefox. But I can also pull tabs into a new window and they will display correctly. And then when I pull the tab back to the original window, it keeps displaying correctly for a while. You can see this in this video: https://drive.google.com/file/d/1VessuiTPlstsp3yH0h0QAG5o7Sc9gZ7E/view?usp=sharing You can also see in the video, around 15 seconds, that LastPass plugin is slowing down firefox, which may offer some clues. But I don't see this very often in this situation. This may have been a fluke. OS: Windows 10 Home on both. Kept up to date with updates. Firefox Version 69.0.1 (64-bit). This has been happening for at least a year. Firefox is updated regularly. I have most plugins disabled that I don't use regularly. Activated plugins: Firefox Multiaccount containers LastPass Simple Tab groups Wappalyzer