YMMV, but on my phone (HTC One M8), Facebook is almost always the top battery user as shown in the Android battery usage report.
And on my old phone (a venerable HTC Desire HD), Facebook's decision to make me install Messenger in addition to the regular app some time ago was the turning point from low latency and good user experience to overall lag in the phone.
And on my old phone (a venerable HTC Desire HD), Facebook's decision to make me install Messenger in addition to the regular app some time ago was the turning point from low latency and good user experience to overall lag in the phone.