The single most effective thing to speedup my droid razr was to set Background Data Restricted from the Smart Actions app.
Trigger: "It's during a specific time" => set to "Always"
Actions: "Adjust Background Data" => set to "Only when using that app"
Most apps are constantly accessing the internet connection in the background in the interest of keeping the app current. But I found there is only a minor lag when starting an app such as gmail. Merely takes an extra second to sync email messages when I fire the app up.