I have the CPU load monitor on my desktop and was wondering for quite some time now over hight CPU loads of 40-60% continuously. Sometimes I just killed plasmashell and started it again. The load problem was gone for a few minutes but came back eventually. Today I removed the CPU load monitor from my desktop but the high load remained. After restarting plasmashell, the load fell below 10% and did not rise again. When I then added the CPU load monitor again, the high load came back immediately.
This bug may be related to bug #380939
Plasma 5.19 unveiled a set of new system monitor applets that use a hardware-accelerated rendering system, so they should not cause noticeable CPU load unless your graphics hardware is very very slow and it automatically offloads work from the GPU to the CPU. So I would expect this to be much improved. Can you see if the problem is still happening with the new ones? Thanks!
Had some system monitor widgets with several configurations running for two days now and they behaved well. :)
Excellent! Behold the power of GPU acceleration!
... and on my side that's a UHD 605 graphics chip from the Intel N5000 CPU, so very low end. :)