I thought so too, but it's just a figment of my imagination. I've got 2 phones here one jb unlocked 4.2.1 (lots of tweaks ie pphtml themes)and a stock 4.3, doing same thing on both phones at same time the 4.2 is 2% lower after a hour an half. That seems about right to me. So I'd say no it's not worse than 4.2.