iPhone battery and lag..

Hey guys!

Recently, my phone (iPhone 4) has been "buggy", let's say. Whenever it charges, it says 100% yet when I take it out it drops to 97%. It takes me 3 reboots to fix this, and I don't know if it's only me.

Secondly, my phone has been "lagging". Whenever I use another iPhone 4, it doesn't seem to, which really "bugs" me. Is it due to the new update or am I the only one experiencing this?

If needed, I can give you a list of the apps I have on my phone..