Sounds very similar to this user is experiencing: After most recent roon and data base updates search is not working - Support - Roon Labs Community
We’ve had an issue that was causing issues with large libraries. The latest update should address them.
If you’re unable to update, as a workaround I’d advise the same as in the other thread: try to reduce or disable the local storage.
BTW at least for search, your machine is definitely fine, even with that library size. It mainly needs lots of memory, and you have that. I have a very similar setup, although way smaller library.l