Battery drain on 5.1.1 update for SGP321

I had installed the new pre-rooted Android 5.1.1 update for Sony Xperia Tablet Z LTE (Pollux). I faced severe battery drain even when the stamina mode and low battery mode were ON. I had around 35% battery level and i was chatting with my girlfriend on facebook messenger app. In just an hour the Tablet shut down itself and the battery was empty! :eek: I have disabled most of the bloatwares even google app and google+.... And i use greenify (Paid version) where i've hibernated all of the installed apps and some of the system apps. Still i had to face this severe battery drain. Is it the problem with new update? :crying: I had installed pre-rooted 10.7.A.0.222 R2E for Tablet Z LTE. It's crazy! Any suggestions? Or please can anybody confirm this issue? Thanks