Tonight I am experiencing the first slow down on my PB, but I am transferring 10GbB via wifi, playing music, downloading an album from the music store, playing a game, and surfing the web... I also downloaded several free games but those went real quick. I am doing this as a test just to see what I can do to slow it down.
The slowness isn't really noticeable but since I am watching for it I notice it.