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 (bug 1696305).
What you are seeing is a known performance problem, but you have discovered a great test case for it in the Resources tab. So thanks. As I suspected, this is not a problem with the new Firefox at all (which is hardware rendered). It's a problem with gnome-system-monitor, or any frequently-redrawing software rendered (e.g. Gnome) app. I only have two more questions: What is your display resolution, and are you using Wayland or Xorg? Both of these can be answered by running 'xrandr' and sending us the output. -- You received this bug notification because you are a member of Ubuntu Desktop Bugs, which is subscribed to gnome-shell in Ubuntu. https://bugs.launchpad.net/bugs/1773502 Title: High CPU usage in gnome-shell & Xorg when using gnome-system-monitor's Resources tab To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/gnome-shell/+bug/1773502/+subscriptions -- desktop-bugs mailing list firstname.lastname@example.org https://lists.ubuntu.com/mailman/listinfo/desktop-bugs