- Firefox is unbearably slow and is consuming 100% CPU, I can barely type this post
- games are running at slide show speed
- GUI is noticeable slow(ish), too
Solved. By adding
Section "Files" ModulePath "/usr/lib/nvidia/xorg" ModulePath "/usr/lib/xorg/modules" EndSection
/etc/X11/mhwd.d/nvidia.conf (the problem was loading the “wrong”
libglx.so with llvmpipe as a renderer) (as suggested in this Ubuntu thread)
More experienced forum members: please help me to improve this post.