I expect this post will just get lost in the crowd but I'm sure it wasn't the efficiency of the code that the OP was upset with – animation lengths are chosen deliberately, and all of them are in my mind set to be far too slow.
I've used a jailbroken device (not my own) fairly extensively who's got little else but a tweak that enables customisation of animation speeds throughout iOS and I can attest to how much more fluid using the device feels when they're less than half of the standard speed. It actually allows you to get things done quicker as there's no lag or unresponsiveness, so in iOS 6 (.1.2) it's clear how the animations are entirely aesthetic (and functionally limiting) and not there to hide any loading.
There are other deliberate design choices in iOS 7 aside from the new animations, some of which I've seen harped on about in other threads that are really worth complaining about:
First in Safari to refresh the page two taps are required instead of one to get to the top of the page without scrolling, in the Clock app's World Clock view the current times were displayed as digital and analogue side by side but now in favour of a spacious white column the user must tap any of the clocks in order to switch view.
While multiple apps can be closed at once from the multitasking view you can only open from a choice of three (one less than before) without resorting to scrolling making it too slower than before, less apps are now viewable in a folder without swiping – and the folder opening animation is still slower than a swipe between homescreen pages!
The bright white "content focussed" interface can cause eye fatigue for some meaning that screen brightness has to be reduced.. making your content harder to see.
The one place I've noticed that Apple have stripped out an animation is the shutter that snaps closed upon capture of a photo which for no apparent reason also means that the photo just taken is no longer held on screen momentarily – the only way to see if another, less blurry, attempt needs taken is to tap the thumbnail and open it fully.
Potentially useful additions to iOS like a system-wide "Use Last Photo Taken" control or displaying items in the Photos app (on iPhone) in the correct aspect ratio (like on iPad) instead of cropping the longer axis to leave a square seem to have been ignored and the functions that have been added are half-hearted; why not have the clock icon change from a ticking clock to a countdown timer if a timer is active, (provided the same colours and associated proportions are retained of course)? Why can't the countdown appear beside the Clock app shortcut in Control Centre?