I dont think Wazapp is the origin of the drain. Mine goes from 15-25 mAh on wifi, (without PSM) to 55 mAh on 3G (again withouth PSM)

My email is updated every 10 minutes, and Wazapp is always on. No other IM client is online. FB and Twitter update every 10 minutes on their own.

I recently instaled Faster N9 which really improved my battery life (its on this forum, search it)