This may be too little too late and may not work anyway, but have you tried resetting all settings?
Settings>General>Reset>Reset All Settings. You will have to enter all of your device settings again.... All of the settings in the settings app will have to be re-entered. Brightness and wallpaper, Safari settings, WiFi password, sign into FaceTime and Messages again, the Privacy Settings - everything will have to be reset to your preferences.
I tried this a couple of weeks ago for a bizarre issue in my settings app, and it did clear up the issue, but it also cleared up my "other" on my iPad which was starting to grow much larger than it should have been.
What this told me was that there was something corrupt on my iPad and resetting all of the settings sort of gave it a shot in the arm for lack of a better term. It really made a difference in the iPad's performance.