Oh KitKat, I really wanted to like you. You took my perfectly functional Nexus7 and its silky smooth menus and app switching and wrecked it. Now I have a whole lot of hurry up and wait. Wait. WAIT!
I haven't been this frustrated with an operating system since Windows 95.
Well, it appears the the solution is really simple: Wipe and Reinstall.
If you've been backing up your device into the cloud, google will automatically reinstall all your apps, contacts etc when you login. My guess is my device was really full when KitKat installed and really needed more space than I had.
If you're a nexus 7 user about to throw away your tablet, give this a try first.