It shouldn't be that exaggerated, but the same way that your laptop takes a battery hit when you reboot it, your phone will too. ~4 minutes of the CPU and every other module in the unit running at full tilt will do that
When I do a battery pull I may drop 5-7%, but if I immediately do a second battery pull I only lose 1%... Subsequent batt pulls then only drop 1%... This has been my experience.
i did 2 battery pulls just to 'confirm' I lost 2%.. (I waited approx 5-8 minutes in between each) to make sure everything was completely loaded.. clicked on options and loaded all my ccurent apps just to make sure the hour glass went away.. I dunno