Me too with a 2014 Retina iMac. There were some quirks with Big Sur Release but 11.1 upgrade ruined the fun completely. A separate account seems to help, but I am really afraid of moving all my stuff to one. I develop xplatform and created an installer setup with a Parallels Windos vm for my Mac compiled app – and I don’t, don’t, don’t want to set all the pathes manually again. Disabling Dropbox and CreativeCloud brought some relief, but once I build apps things are starting to slow down again tremendously. But at least no kernel panics and no enforced user account relogins anymore for a whole day now. I noticed that my Mac has a tendency to use only half of its memory. After one day of uptime, I still have almost 14 Gigs of 32 marked as free, but the system swap file is 3 GB in size,using half of it actively. Shouldn’t it only start to page that heavily when RAM is really used up?