Nevermind, it's obvious you're using Xorg sessions.
At what resolution though? Please just run 'xrandr' and send us the
output.
** Summary changed:
- High CPU usage in gnome-shell & Xorg when using Firefox
+ High CPU usage in gnome-shell & Xorg when using gnome-system-monitor's
Resources tab
Oooh... that makes sense now, thanks.
The problem you are seeing is with mutter/gnome-shell being inefficient
at frequently-updating software rendered windows. This is a known
problem, but until now we only knew of Eclipse triggering it (bug
1756508), and the older pre-Quantum versions of Firefox
I restarted my computer 3 time.I launched FF and the top command. The home page
of FF is https://www.bing.com/?cc=be. I opened a second tab with
maps.google.com. Everything was find. I lauched system monitor and then, the
CPU of one core jumped to 100 %, even after closing the maps.google.com
