Unusable Ubuntu 18.04

I have a couple of desktops with Ubuntu 18.04 and in the last few weeks using them has been a pain:

  • If I have windows of different programs opened, I need to Alt+Tab to switch between them, and sometimes that also doesn’t work
  • Windows freeze / become unresponsive at random
  • The system performance gets worse as you use it

I reinstalled from scratch and that didn’t fix the issue. I noticed the same behavior on two machines: one equipped with a GTX 1080 and one equipped with a 2080Ti.

At the moment only the one with a GTX 1080 is usable. I am running CUDA 10.2 with the 440.33.01 driver.

I have the same issue both with the Ubuntu and with the Gnome desktop environment.

Do you have any suggestions on how to fix the issue? Thanks