Created attachment 128468 [details] screenshot STEPS TO REPRODUCE 1. have dozens of window rules configured on your system 2. open system activity by pressing ctrl+esc 3. open system settings > window management > window rules 4. scroll the window rules list and observe the cpu usage OBSERVED RESULT high cpu usage, see the attached screenshot taken on X11 please. On Wayland cpu usage is even worst, sometimes reaching 50% on my system. EXPECTED RESULT normal cpu usage SOFTWARE/OS VERSIONS Operating System: Arch Linux KDE Plasma Version: 5.18.90 KDE Frameworks Version: 5.70.0 Qt Version: 5.15.0 rc2
I tried adding tons of empty rules and scroll in the list and I can see the high CPU usage but also lagging.
As I'm super lazy, could you export your rules and attach?
Created attachment 129199 [details] my rules Of course.
Thanks for the rules attachment. I think I found the cause. Submitting a fix.
Git commit e307038f84dc0fc0556b2ceb259da0c09b035ce1 by Ismael Asensio. Committed on 10/06/2020 at 21:29. Pushed by iasensio into branch 'Plasma/5.19'. [kcm/kwinrules] Fix slow scrolling through rules list Every `AbstractItemDelegate` was instantiating a `Kirigami.ActionToolBar`, which is a very expensive component, rising CPU usage specially on long lists. Use `Kirigami.SwipeListItem` instead, as is seems the proper component. M +23 -30 kcmkwin/kwinrules/package/contents/ui/RulesList.qml https://invent.kde.org/plasma/kwin/commit/e307038f84dc0fc0556b2ceb259da0c09b035ce1