After receiving updates to gnome-shell (now 3.26.2, was 3.26.1) and reboot issue not observed anymore. So I close bug.
** Changed in: gnome-shell (Ubuntu) Status: Triaged => Invalid -- 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/1735389 Title: gnome-shell under gdm user eats more CPU than other processes To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/gnome-shell/+bug/1735389/+subscriptions -- desktop-bugs mailing list desktop-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/desktop-bugs