I think it has to do with the size of the database of the ``Now Playing'' shows. But that's really just an educated guess.

I just read up on the Tivo Cachecard, and yes, the slowness of the Tivo menu is due to the database.

From what I gleaned from the Tivo Cachecard site, the database is all hard-disk-based, and the player doesn't have a lot of cache RAM. So when it's streaming video to its disk drive, database reads and writes take a back seat to the actual video streaming. That's why the guide menu is so slow, and why doing database-intensive operations like rearranging your season passes is painfully slow.

Unfortunately, the Tivo Cachecard isn't available for the Series 2 units yet.