Get rid of McAfee for now, and recharge the phone to 100%, then clear caches, and also clear it with Volume Up + Power, while the device is on(until device vibrates and display turns off).
Then check how it is for the next 8 hours.
Reinstall McAfee, and then charge it to 100%, then check how the battery performs after another 8 hours
edit: this is what i'd do -
plug the phone in to a wall charger, then use volume up + power to get the device to turn off, wait for the charging battery to appear and start it's animation, then power on the device while it's still in the charger and charge it to 100%, then clear the caches, and use vol up + power
2nd edit: then go and disable any google services they turned back on during the upgrade if you don't use it.... like nearby and other junk like maps notifications
3rd edit: then go and take advantage of the 'new' (for you coming from android 6.0) features in data usage to disable any background data for any junk you don't want using background data for...
namely facebook. and then go and disable any google apps you don't use... like hangouts, and then restrict the background data for 'google instant apps' - if you're not going to use it and it appears - don't uninstall it - it'll just come back
