Basically, any trouble that I've had prior to this has been negligible and easily resolved.
I don't recall, exactly, when these two issues began. Possibly months after upgrading to Catalina. I'm combining the two issues because I believe that they be related.
The first issue that I noticed was with Firefox (probably 70.0.1 and slightly earlier). I would have two or three tabs open, and go back to one of the other tabs, to find a completely white screen with a grayish colored pinwheel. I'd then go back to one of the other tabs to find the same thing (that was previously not happening. Then, I'd close all the tabs to open a new one in order to try starting fresh. No dice...same shit.
Following this I'd select > Firefox > Quit Firefox. Minutes later it's still not quitting indicated by the black dot under the icon of the launch bar. So, I'd go to the apple icon > Force Quit > to execute that. Finally, it would quit. Minutes later I'd try to reopen Firefox and the icon would just keep jumping up and down from the launch bar and nothing would happen.
I guess I'll just have to restart the computer then, right? Apple icon > Restart > several minutes later nothing would happen except for another grayed out pinwheel. So, I just performed a hard reset by holding in the power button on the back left of the screen. Waited several minutes, started it up again by quickly pressing the same button.
After logging into my account, I'd get the usual text box saying that 'Your computer was restarted because of a problem...blah...blah...blah'. All of the aforementioned took many minutes.
Now, when I try to shutdown my iMac it just goes black and then returns to the login screen with a brief black screen, in several languages (Chinese being one of them), that 'You have restarted your computer.....'
And Firefox keeps fucking up as described above. Going to about:crashes registers jack shit.
It's a never-ending loop of Mac/Firefox bullshit that's driving me fucking nuts.