Here's how I speed up my LOLLIPOPed Nexus 7 2012. (From now on let's all use "lollipop" as a verb that means screwed-over by an update). These steps are all easy to do and reversible.
- Settings > About tablet > tap on the "Build number" entry seven times, which will unlock "Developer Options".
- Settings > Developer options > Set WINDOW ANIMATION SCALE, TRANSITION ANIMATION SCALE and ANIMATOR DURATION SCALE all to ANIMATION OFF
- Settings > Developer Options > Background process limit > at most 3 processes