(machine translated in 2018) My Nexus 7 (2012) got updated to Android 5. It became really slow. I found some really usefull tips to speed up my Nexus 7 again.
A lot of tips on the internet are about removing unused apps and clearing caches, of course this helps. But tips your rarely find seem to have bigger impact.
I found that:
2) going into keyboard settings and choosing holo theme
3) keyboard settings-> gesture typing-> turn off dynamic floating preview helped a lot.
4) turn off google voice input
Swipe down twice from the top of the screen in order to access the settings toggle menu.
Tap on the wrench-shaped icon near the top-right of the screen to open the settings page. Alternatively, access the settings "app" by navigating to it through the regular app drawer.
Scroll down to the "Personal" section and tap on "Language