I had high CPU and unresponsive gnome desktop on older Ubuntu virtual machine that was upgraded to 18.04 LTS from earlier past LTS versions on VirtualBox 5.2.18 or earlier running on Windows 10. The high gnome-shell CPU and unresponsiveness was randomly triggeded eg. by resizing application windows. I was able to switch to text virtual terminal using Ctrl-Alt-Fn and the gnome-shell CPU load decreased while in text mode. It has not occurred since I changed using gnome-tweaks the application appearance to Adwaita.
I recently installed a new 18.04 LTS that also became unresponsive at similar application or VirtualBox window resize. I am not 100% sure if this is same problem as I have VirtualBox 5.2.22 now and I was unable to change to text virtual terminal after VirtualBox window resize. This hang happened at least on VirtualBox windows resize. The virtual machine was able to shutdown through ACPI. I changed to Adwaita from Ambience and now I have been able to change window sizes without hang. Due to randomness, hard to say this problem is completely gone by theme change. gnome-tweaks shows no extensions enabled. Now at gnome-shell 3.28.2-0ubuntu0.18.04.1. VirtualBox has 3D acceleration enabled, no 2D acceleration. I have an old AMD Radeon HD 6450 with a bit old drivers from 2015, I noticed. -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1800101 Title: gnome-shell uses 100% CPU To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/gnome-shell/+bug/1800101/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs