The problem is that it starts out with a set of coordinates, then you ask it to transform those to another set 2048, 1536, then to 1536, 2048.
There's a couple of different ways to do the transform, but think about it, the Ipad wasn't made for that kind of activity.
Anyway ios6 portrait looks to be in the 50-60's, and landscape...
acts strange, goes from 10 fps to 60 fps with little activity.
Its almost as if there was some throttle mechanism.