Battery life, I would guess
My Galaxy SII doesn't last through one business day, on 3G/HSDPA and with whatever *slow* processor it has, if I have email "push" switched on. Seriously, on Wednesday, I unplugged it from the charger at 9 a.m., had / made only a few calls (I'd love to state the exact amount of time I spent on calls that day, but the call log lists each call individually and I don't have the patience to go through them and tally it up - definitely not more than an hour's talk time, though, for certain) and by 4 p.m. it was warning about low battery and dead by 6.
It's much better now that I set email to update only every hour but I do still have to charge it every night or it will die before lunchtime the next day.
