I find some of the new transitions annoying, too, but it simply doesn't make any sense to say that they are "to hide choppy performance." We know this because

I find some of the new transitions annoying, too, but it simply doesn't make any sense to say that they are "to hide choppy performance." We know this because the transitions are very smoothly-rendered. Which takes processing power; the animations and such would not be smooth if there was a CPU issue they were trying to cover up. It's an intentional decision. There's plenty of performance under the hood, or they wouldn't be able to afford the extra CPU cycles to draw fancy animations. That being said, I hope they shorten some of these transitions, as well. In many ways, iOS 7 is faster and more responsive, and so it'd be nice if it were faster in this way, too.