I used to have apps in the auto kill list for the stock Task Manager, but I was noticing my phone would slow down and "redraw" a lot, so I removed all apps from that list. Yesterday, my phone was just chilling on my bed, and when I turned the screen on, I saw a message from the system saying that the Facebook app has been running for 45 mins and is using many resources, would I like to shut it down?
I had never seen a message like that before, and when I went to the app, the only thing that it could have been was a friend was messaging me via Fbook, and the messages popped up on my screen using the Fbook app.
This morning when I checked the battery graph, it was almost completely depleted, and the massive drain coincided with that event last night. I'm not sure if the latest Fbook update messed with the battery life, or if this is just a one off event