It gives me the beachball anytime I do anything involving I/O (syncing, adding songs, retrieving album art, calculating gapless bullshit). That's bad UI programming. Do your I/O in a background thread.
I know it's doing it on the GUI thread because I'll command-tab to it and it won't redraw, which of course prevents me from cancelling out of whatever task-I-didn't-ask-for it's doing.
This, btw, is the same behaviour I hated on windows.