After trying many things, I re-booted my system and it was taking forever. There was all kinds of script running and running and running. I went to work, came home, still booting.... 12 hours later. I don't know what I did, but I was about to give up on everything.
It would've been interesting which processes were running at that time exactly. You can see (and maybe show us) the running processes sorted by CPU and memory usage with the command
top, or
htop for a more colorful view. Similarly, the disk activity of processes can be show by
iotop. You may have to install the latter two from the official sources in a standard Ubuntu system, but that means they're only one
sudo apt install htop iotop away.
I know you already gave up, so this is meant as an advice for the future. Many of us long-time Linux users like to examine and maybe solve a problem instead of giving up "too soon"â„¢.
But it's your setup and anything that works for you is okay.
edit: just some wording corrected.