It seems to have fixed itself (maybe another update?). Things are back to normal.

I already maintained the library. I don't think it has anything to do with MM itself, since all I have to do is increase MM process priority to above normal and it behaves like it used to.
I'm thinking some windows update changed something in how the MM exe runs (uac virtualization, or something, don't know) which caused MM to run with lower priority than usual.

EDIT: MM.DB is already in an M2 drive

File > Maintain Library with complete optimization checked is the remedy for this within MediaMonkey.

Outside of MediaMonkey you could see if the database file is fragmented (on disc based hard drives) or if you can move it to a faster drive (like an SSD/M.2).

Hi,
Since about 1-2 weeks ago, autoplaylists are suddenly very slow to load. When that started to happen I updated to the latest beta (don't remember which version I had before) but it remained the same.
If I go to task manager and set MM priority to above normal, autoplaylists then load normally.

I also tried to open the MM.DB with MM5 and maintain the database and save it back to MM4 format, but the problem still remained.

I'm guessing it was a windows update, since I didn't change things anything in MM when it started happening.
I was waiting to see if anyone reported a similar issue, but so far I haven't seen anything in the forum.

EDIT: playlists went from 2-3 seconds to load to about 20+ seconds. I have to change priority on MM everytime I open it.