I can't believe it's not faster. Maybe you have a faulty box.
I stayed at a friend's house who had BT TV and the menus were very slick and fast. When choosing to record a TV programme on a non-hd channel, it would alert me there was an HD option available which is handy (and logical).
The whole system was very intuitive and when opening up a player such as iPlayer, 4OD etc it would load up MUCH faster than Tivo.
The Tivo box takes an age to open up an On Demand app and scrolling through menus is definitely slower than the competition in my opinion.