OneDrive?  Are you storing your collection in the cloud?  I wonder if you wouldn't have better luck copying that locally until you get whatever you need accomplished.

I only mention that because I ran into a similar issues this past weekend.  I'm trying to get my plugin updated for 4.0 and it was taking ages to read my collection (like 100x slower than normal).  It was because I was storing it on a cloud drive.  Profiler seems to have no issues with it.  But for whatever reason, my plugin wasn't the least bit happy.  I moved it local and all it well.  When I'm done playing around, I'll switch it back to the cloud.