Created attachment 156800 [details] load SUMMARY If I scroll through all open apps on panel, ALL apps that I scroll through start consuming significant amount of CPU (around 10% each). Load drops to zero when all apps idling. It virtually doesn't matter if I use it with KDE apps or not (e.g. I tested with firefox, systemmanager and dolphin open). kwin process also gets some load here too. So I suspect that wayland is the culprit here. And since diverse set of apps starts to behave in a same way I have some doubts that firefox, systemmanager and dolphin all have same bug at the same time. Well, it could be wayland-client bug still but that's out of scope of what I am able to debug. STEPS TO REPRODUCE 1. Open some apps 2. Scroll through tasks rapidly using task applet OBSERVED RESULT Significant CPU usage for all apps involved EXPECTED RESULT Something more moderate I guess? SOFTWARE/OS VERSIONS Operating System: Arch Linux KDE Plasma Version: 5.27.1 KDE Frameworks Version: 5.103.0 Qt Version: 5.15.8 Kernel Version: 6.1.12-zen1-1-zen (64-bit) Graphics Platform: Wayland Graphics Processor: AMD Radeon RX Vega M GL Graphics
When you do this, KWin is rapidly showing and hiding them, and there are animated transitions, shadows, possible transparency and blur, etc. Not sure There's really a bug here. When you ask the system to do something hard, it takes some resources. :)
(In reply to Nate Graham from comment #1) > When you ask the system to do something hard, it > takes some resources. :) I'd agree if only kwin was consuming resources. But it also causes apps to consume quite significant amount of CPU cycles while apps themselves basically not doing any active work. So there's probably something funny going on during interaction between compositor and apps and that is what doesn't seem like a normal thing to me.
I also checked out X11 session and well, if you do this there, CPU usage for all processes is less than 10-12%. From that, Xorg and plasmashell processes consume more than half. So I am pretty sure that this is quite significant issue when same actions now take 5x more CPU time than old times.
Ok, let's see what KWin people have to say about it.
Thank you for the bug report. Unfortunately we were not able to get to it yet. Can we ask you to please check if this is still an issue with Plasma 6.3.4 (the latest released version)?
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(In reply to TraceyC from comment #5) > Thank you for the bug report. Unfortunately we were not able to get to it > yet. Can we ask you to please check if this is still an issue with Plasma > 6.3.4 (the latest released version)? As of 6.3.4 situation doesn't seem to be different. You start scrolling through apps, CPU consumption for opened app increases. But on X11 only plasmashell CPU usage increases significantly. If plasma consumes ~2% CPU idling, during rapid scrolling (both on X11 and Wayland) it consumes about 10-12%. But on Wayland ALL opened apps also start eating CPU which doesn't happen on X11. I don't use wayland regularly for a number of reasons so it took some time for me to check it.
Thanks for re-testing. The KWin developers will have to take things from here. For what it's worth, I'm not able to reproduce this on git-master Wayland
Created attachment 183130 [details] scrolling (In reply to TraceyC from comment #8) > For what it's worth, I'm not able to reproduce this on git-master Wayland It's likely a cheating since after update to 6.4 default action for scrolling is "do nothing". When you enable scrolling, it's all the same again. See how thunderbird having 10% load just because it's participating in scrolling. Compare that to IDLE (which will be in the next screenshot).
Created attachment 183131 [details] idle
Created attachment 183133 [details] scrolling
Created attachment 183134 [details] scrolling third time's a charm I hope