From what I can tell the CPU/GPU of the Nexus 7 surpasses those of the Galaxy Nexus ?

In my experience with the Nexus 7, Project Butter didn't achieve all of its goals at eliminating input lag and the like.

Certainly those random pauses you saw scrolling around on previous Android devices are all but gone*. But things are still not as smooth as iOS.

It is apparent (though subtly so) in many areas, but one noticeable case stands out. Slow speed tracking is still very poor compared to iOS.

What I mean is when you drag something slowly around the screen you expect it to move smoothly with your finger. Which is exactly what you see on iOS, a buttery smooth movement.

On the Nexus 7 however you don't get a buttery smooth movement. Instead the display jerks a couple of pixels at a time i.e. drag finger slowly, display moves a bit, keep dragging, display stops moving, keep dragging, display jerks a couple of pixels and catches up with your finger. This will continue like this all the way across the screen, it seems incapable of moving the display by less than a couple of pixels at a time.

The end result is jerky and not at all buttery. From what I can tell it doesn't matter what app you are in, the same roughness of movement is there system wide.

Of course it maybe that the problem is down to the digitiser in the Nexus 7, I have no idea as I have no other Android 4.1 devices to compare it to.

* the one place it still rears its ugly head is in the Play Store. But then the UIWebViews used in iOS's App Store can be equally laggy, so that one is a draw