Immediately after the Upgrade from 8.0, I Hard Reset the phone WITHOUT restoring my old backup, and started as new.
Then, after two full discharge and recharge, my Battery lasts even LONGER than 8.0 (on Nokia Lumia 920 here).
That's what I also tweaked:
1) Turned OFF: Bluetooth, NFC, Wi-Fi Sense, Data Sense, Touch High Sensitivity, Find my Phone (save position), Announce ID, Microsoft Feedback Reporting (on IE, Keyboard, Wi-Fi and Bing) AND Battery Saver (both the main switch AND Background Setting);
2) Background Tasks: Disabled most of them, and kept only the essential ones (Whatsapp, Facebook, Store, Skype etc);
3) Mail Sync: every 1 Hour;
4) Settings Sync: all Disabled;
5) Lockscreen image: Static, from Photo;
6) IE: set Webpage compression to Standard, Find location Disabled;
7) Bing: find location Disabled;
8) Integration Hub: only 1 Microsoft Account (Outlook mail check included inside this) + Twitter Account + LinkedIn Account.
My phone last all day under heavy usage, and drops 1% every 2-3 Hours.
Very satisfied, and I already know that after Cyan it will be even better :smile: