The GPS receiver is probably sucking power, just like the 12-100 does.
Agree, about not turning the GPS off.
I had a couple people say to turn off the IS on the 12-100, for high shutter speed daylight pics, to extend the battery life. But I really LIKE the way the IS stabilizes the image in the EVF, and makes it MUCH easier to hold the lens on the subject. So NO, I won't turn the IS off, it has value.
It is sucking power but like you will not turn it off. I also like the stabilized view and never turn off IS either. Even when shooting my original EM1 and knowing it would effect CAF ability due to limited processing power I would keep it on for the stabilized view.