This is only the first beta of iOS 7. Considering that this is the largest change to iOS since its release and that it's usual for things to change over the course of a normal beta, you can be absolutely certain that there will be a lot of UI improvements to it over the coming months.
Quote:I never owned an iPhone 4. My 4S is running it well though it does lag here and there but I'd put that down to it being the first beta. Apparently some effects are disabled on the iPhone 4 and no doubt it's not as snappy as the 4S but I can't say for certain.