i have ubuntu vivid updated to latest packages with dist-upgrade on my netbook with atom n2600 (powervr gpu). i have a simple alt-tab switcher that displays windows as large icons on the bar appearing on the left side. Reproducible: Always Steps to Reproduce: sometimes (usually 10 times trying is enough) when i press alt+tab the desktop freezes totally. only mouse pointer can be moved. i switched to console with ctrl+alt+f2 and saw that kded5 and kwin are eating 100% of cpu. i attached gdb to them and issued 'bt' command, then 'c' and waited few seconds then 'bt' again and so on. you can find output in files attached. i had this freeze in vivd alpha1 as well, so it is not very new issue.
Created attachment 90634 [details] kwin backtraces
Created attachment 90635 [details] kded backtraces at first the alt+tab freezes only for a second. but if i continue using it, it will freeze totally, and i will have to reboot ;(
likely bug #340294 -is that with the default breeze switcher (the vertical bar on the left side)?
yes *** This bug has been marked as a duplicate of bug 340294 ***