I notice that you fixed the memory problem.
Now to try to fix your second problem install
this , open the config window (/baudmanager), check the
Track CPU Usage box and reload UI. Search for the addon that use the most CPU time, disable it and try again to see if you still have glitchs. The best way to test addons, imo, is to go to AV.
Also what is your graphic card model? I have some drivers for nvidia