Is there a way to force photoanalysisd to work harder than it does by default?
I had the same problem when I migrated all my photo library and here's the way I've found to make Photos analyze my gallery faster:


Open Photos.app preferences
Open the iCloud tab > click on Download Originals to this Mac
Wait for all the photos to download




The scan should be faster after this, it should scan ~50 000 pictures per day. Unfortunately, if you don't use iCloud or the "Download Originals" option was already clicked I don't think there's any other way to make it go faster.