Hi Markus,
That’s really weird!
I cannot reproduce this in 2.83 (or other versions I tried); the set Frame Rate is never exceded in the Viewport in my tests:

That’s not just a bug, that’s an ‘Überbug’…ordering 6 chickenwings and getting 6 whole chicken…
My first guess would be a driver issue, but that usually makes things worse, not ‘better’…🤔
Let me sleep on this…
…and while I sleep, maybe @waylow the Wise knows…