My problem is connected but not exactly same. I upgraded my iPad 4 from IOS6.0.1 to IOS6.1 then very obvious I saw battery usage about 1.5 times faster than before. And the game ASPHALT 7 slowed down a lot than before. I'm exploring how other apps are affected.
I made the bad move to upgrade my iPhone from Ios5 to Ios6. I can't believe I stepped into the same hole again. In future I will NEVER upgrade IOS unless an immediate need.