I am using Windows 11 and creating a KODI music collection. When I export the library to my "Artist Information" folder Opus just freezes and stops responding if I have the artist info folder in focus. This export creates several hundred files.
I can continue browse the same folder in File Explorer and One Commander without problem. Opus remains frozen even after the export. I have to kill it or wait at least 5-10 minutes before Opus responds.
Initially I thought it might be the auto folder size calculation, but turning this off makes no difference.
It looks like the Folder Tree is the problem, as it's doing a lot of work to update itself for all the filesystem activity (and it potentially has to keep track of or at least consider changes to every folder on every drive, depending on what's expanded).
If you close the folder tree while doing that export, I'd expect CPU usage to return to normal.
If Preferences / Folder Tree / Contents / Zip files and other archives is on, turning it off may also help, as it lets the tree ignore events involving archive files.