The cause of the jelly scrolling is generally thought to be that the screen and display controller were optimized for scrolling as though the mini was in landscape mode. When you scroll in portrait orientation, the updates have to be done 90 degrees across the actually physical pixel update sequence. The result is mismatched updates in adjacent parts of the screen. Not everyone’s eyes are sensitive to the effect depending on their response rate. This rumor says that they are swapping the orientation of the screen components to favor portrait orientation scrolling.
I get that. But they make it sound like jelly scrolling has to exist one way or the other. If that's true, how come the jelly scroll is seemingly much worse on the Mini than other iPads? (Obviously, I'm only referring to people who see it at all).
Is it purely down to the smaller screen size of the Mini? I've no doubt the re-orientation of the screen components will improve the experience, at least in portrait. But is that really the best Apple can do?