There seems to be a general problem with widget redraws taking up undesirable amounts of CPU e.g. https://bugs.kde.org/show_bug.cgi?id=356479, and MANY similar going back years. If you can live without animated widgets, life is good.
Is this devil going to kill KDE? It was a very nice project. One user wrote in 2016 on the website of in the KDE Bugtracking System (https://bugs.kde.org/show_bug.cgi?id=356479)
“I’m getting high CPU usage on plasmashell even without any animation quite often.”
The KDE community seems to be going after the wrapping rather than the cookie. They issue defective plasma after plasma… (Since long I had a suspicion that plasma is bad for humans - it contains too many free radicals.)