I have a smallish (3000 track) iTunes library of classical music, on an external drive. Artwork usually has to be added manually. Until a few days ago, adding artwork to an album via the Get Info pane was slow but tolerable. Now, suddenly, it can take 20 or 30 minutes for a single album. The snail-like progress shows in the "Processing" window, but otherwise iTunes is unresponsive (spinning beach ball if you click in the main window). The Activity Monitor doesn't seem to show anything weird (and very low CPU usage by iTunes). Any helpful suggestions how to get back to something like normality?