My AppleTV2 takes 3-8 minutes to load individual menu screens when trying to sync to my iMac. I get the spinning gear and "Importing iMac Library". I have to watch another show and flip back and forth until the thumbnails appear.
Wireless G connection, Airport Extreme 42' away, through two interior walls. Signal strength is five bars on the Apple TV. The videos play flawlessly once they eventually show up.

1) My iTunes folder contains about 1 Tb of H.264 movies. Is this just too much data?
2) The Xbox 360 that the AppleTV replaced cued up my library is seconds using NullRiver's Xbox Connect. The menu's just sucked to navigate.

The AppleTV works great playing Netflix movies and menu's are great, but I sucks waiting for stuff to load.