Finder was unusably sluggish since I upgraded to Big Sur. It took over a minute to open a Finder window. ActivityMonitor showed the Finder never went below 100% CPU usage.
I tried all the tips I found here and elsewhere on the web, to no avail.
To see whether the problem was connected to my user account, I created a Guest user account, and logged in as Guest. The CPU usage went below 4% and stayed there.
Logging back into my own account, I closed all my applications, one by one, to no avail.
Then I closed all my Finder windows (almost all of which had already been open in Catalina), and watched the CPU usage go down as each window closed.
Close all your old Finder windows!
Reopen them anew in Big Sur.
AndreasW
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