I have a Nexus 7, and the battery life has been a problem, just looked at the use data, and the NFC pulled 38%, more than Android system.
Have never used it, just turned it off.
That's very strange.
NFC only transmits while the screen is on and the device unlocked, and the working distance is about 2cm, so it shouldn't use much power at all.
Give me some examples on how you use nfc thanks!