I have installed Android 5.0 on my Nexus 7 (2012, wi-fi) and that was the biggest mistake I have ever done with my tablet pc. I don't know, maybe the problem is not in Android Lollipop, but in my concrete device, but after installing 5.0 it becomes incredibly slow! First 5 minutes after restart it works fine, but then everything become soooo sloooow.... Here are some steps that can help you with downgrading your Nexus device (5 or 7) from  5.0 to 4.4 (or whatever you want). Download factory imag...