Read in a youtube comment that he has graphics thingy turned off, that's why it is slow. So I hope it will be as good as stock siri, just give some 3-4 days...
As of now no one knows motives of Apple. If they make Siri exclusive just for i4s then we have JB community & it will make everyone to JB
The reason cited for the sluggishness is attributed to some special GPU drivers for the iP 4 which does not seem to be included in the iP 4S' binary cache.
see do what may by JB, but it can't be as smooth as the original one. Apple puts billions of dollars in these reserch... never seen a JB app which doesn't effect system performance in one ways or other...