This might have to do with the latest nvidia drivers 510.47.03 and it may not, somewhere around when they arrived this started anyway.
It goes like this: the machine is suspended and then wakes and for five minutes after is rather unresponsive. If I am patient and get btm running in a terminal window I can see that the CPU is getting a workout and the RAM usage is going up up and that the plasmashell process appears to be the culprit. After a minute or two kswapd0 starts and swap usage goes up up. When both swap and RAM are maxed most of the plasma UI disappears and reappears and then the CPU workout and RAM usage ebb out.
It does not happen on every wake from suspend; maybe every other or every third. I suspend the machine several times a day.
I might try running noveau for a little while but I can’t play a single game in my Steam library with those so for the moment I’d like to ask if someone else has encountered anything similar?