One thing about having a Nexus 7 is that new versions of Andriod come to you quite quickly. I was quite interested to see what the new KitKat version would do to the tablet. I wasn't so impressed: suddenly it was glitchy and unresponsive. Given the whole release was about improving memory usage and performance I thought it was odd. I couldn't see that KitKat should break the tablet even though it was the first edition.
I discovered that by wiping the cache partition improves the performance, and I now have my tablet back. Next time your tablet or nexus phone seems slow: it's worth remembering this trick.