Time to clear up what i said here, here and in some other messages a few months ago, as i've already revealed it on IRC.
One of the Wii U core wasn't used throughout the development of several launch window games. It's an "engine related issue", meaning it's the way the teams behind those titles have programmed their engine for the Wii U CPU. It wasn't widespread, not universally seen on all the games, but witnessed on at least a few of those. The developers found and resolved this problem mere months/weeks prior release, and most of them gained a nice increase in FPS. It's one the origin of the huge boost in framerate i reported a long time ago that some studios managed to get (from 30 fps to 60 fps for some games), along with new dev kits, etc.
You heard it right, a whole core of the Wii U CPU wasn't put in use for most of the dev cycle of several titles, before it was fixed.
It's rather telling either: - on the crucial need of studios, accustomed to the HD-Twins framework, to adapt their code to the Wii U specifics - or the perfectible state of documentation/dev kit/SDK's at the time - or [insert your own conclusion/guess derived from this info]
