I upgraded my 2012 Nexus 7 to Lollipop and it is s-l-o-w. I mean, really really slow. 9 seconds for the home button to return me to the home screen. 7 seconds for screen rotation to occur after I physically rotate the device. 6 seconds to open Chrome. This device was already slow before, but Lollipop (or some glitch triggered by the Lollipop update) made it dramatically worse.