have you setup autokiller? if not, set it for either moderate or aggressive (I use aggressive settings). make sure you don't have Setcpu or overclock widget installed. both will cause slowness.
as far as battery life.. what kind of signal do you have? a lot of schools get very poor signal due to the construction of the building. if you get 1 bar, or if you have a high TWS (Time Without Signal) you will eat up more battery due to the phone trying to boost it's power to reach a signal.
to check TWS, go to menu>settings>about phone>Battery>Battery Use>Cell Standby you can also see if anything is running and using a lot of CPU time from menu>settings>about phone>Battery>Battery Use
or download spare parts from the market and see what is using most of the CPU or battery