This happened to me that when I updated it reset some of my settings.
Here is what I did, go through your settings and
- Turn off push notifications.
- Adjust the screen brightness, mine had changed and you dont need it full brightness, set it back to where you had it.
- Make sure background app refresh is OFF. That will drain your battery always checking and updating apps.
- Turn off "listen for siri". I activate siri only when I press the home button. I dont want anything draining my battery that I'm not using.