A few days after installing 8.1 I did a hard reset to see if it would help out some of the problems, which included battery life, freezes and lag. During the setup I chose to restore from backup. The reset didn't seem to help. Yesterday I did another hard reset, but didn't do the backup restore, and reinstalled my apps manually. The battery drain is still there, but everything else is working smoothly. In fact, my 1520 seems to be running faster than before I installed 8.1. I've done everything I could to help out battery life, such as killing all the background tasks, syncing email manually, etc. I've read that some people had the battery life improve several days after a reset. Hopefully that happens.