My battery was draining fast also. I turned off WiFi today when I was out of the house. Battery improved a lot. Bluetooth was on but not connected to anything. But just turning off WiFi made a lot of difference.
I have the P10P XL. It was mediocre the first few days. I work in an ER with variable reception. After a normal 10h shift with my 9P XL I'd be down around 70%. My 8 was closer to 60%. I've had the phone since launch day and yesterday at work I was draining fast. Today I left my 10h shift in the same place at 82%! More data needed, but that's crazy good.