I have a pi zero w, with I think around 1000 albums on a USB (mp3s). It does freeze up after updating music on the USB. It takes about 10 minutes for the initial indexing, but without freezing. Where it freezes is when I click on Artists (or I assume Albums) the first time. It’s frozen right now and I can’t even SSH in.
Last time this happened I think I just waited a few days and it was fine. Since this is happening on clicking Artists, I’m guessing the little pi is overwhelmed trying to add album covers.
Next time I’ll try adding files without disconnecting the USB - hopefully it only has to reindex the added files.