Facebook is looking into claims that its Android app hogs up to 20 per cent of users' battery power.

Even when running in the background, Facebook’s Android software could be significantly impacting battery life and performance, according to a Guardian writer.

Samuel Gibbs claimed that after uninstalling the app, his Nexus 6P saved an extra 20 per cent of battery life on average each day, measured over a week.

The experiment was prompted by findings from Android specialist Russel Holly, as well as Reddit users such as pbrandes_eth and cloudbasejunkie, all of whom reported improved performance after removing the software.

The reason Facebook’s app affects performance and battery life so much is apparently to do with the way it interacts with Android’s core systems.

Gibbs stated that while the app itself was not drawing an excessive amount of power, once uninstalled, the Android System and Android OS processes both showed significant decreases in battery demand.

http://www.itpro.co.uk/android/25969/facebook-investigates-claims-android-app-cuts-battery-life-by-20?

This is a good reason to have a rooted phone. Greenify and Purify do the job for me.

Unless I want an app to run in the background (I'm not a social media junkie) they get hibernated shortly after the screen goes off.