I personally feel the TYL version is slower, in alot of the games I play. But at the same time there are a few that are faster on TYL. Sucks I have to keep both on my mem stick, but thats the way it goes till either Y's gets faster or TYL's gets better/stable.
For example on TYL's MKII is slow at menus but ok in game. On Y's its slow all around.
But on Contra III TYL is slower then hell while Y's is fast.