I'll bite. It's the simple things: selecting a different song to listen to is so painfully slow. It's the task I do probably 10-15 times a day (I'm not much of a playlist builder), and it takes so long to bring WMP up, get to the search bar, filter, and
then play the song. It's pure performance (the UI isn't so bad).
It's even worse when I want to see the list of songs I've purchased through Napster. Those are typically the one-off singles that are running through my head, and it takes an excrutiatingly long time to click to the Napster tab, hit their site, and list the
music I've purchased. There should be an easy way to do that!