I guess it's caused by commit "drm/radeon: disable AGP by default".
Please test latest mainline kernel: https://kernel.ubuntu.com/~kernel-ppa/mainline/v5.10-rc1/amd64/ Hopefully it's already fixed. ** Changed in: linux (Ubuntu) Status: Confirmed => Incomplete -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1899304 Title: Linux 5.4.0-48 (and later) causes GPU lockup, huge performance drop, makes GNOME desktop fail to start and games going from 70fps to 7fps, slow file loading, audio issues To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1899304/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs