This is hitting me too. Some research shows https://bugs.kde.org/show_bug.cgi?id=336592 and an accepted patch. Libxext needs packaging and distributing, as I understand it.
** Bug watch added: KDE Bug Tracking System #336592 https://bugs.kde.org/show_bug.cgi?id=336592 -- You received this bug notification because you are a member of Kubuntu Bugs, which is subscribed to Kubuntu PPA. https://bugs.launchpad.net/bugs/1384512 Title: Plasma 5 frequent screen freezes To manage notifications about this bug go to: https://bugs.launchpad.net/kubuntu-packaging-next/+bug/1384512/+subscriptions -- kubuntu-bugs mailing list kubuntu-b...@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/kubuntu-bugs