mobile

Last night I left my new Nexus 6 with Notifications OFF and all the apps closed at 50% battery, after 7 hours the battery was at 39%, it seem to much to me to use 11% just idle in 7 hours, other phones I've used in similar situations will not use more than 3-5%, please could you share what are the best practices I should follow without having to put the phone is Airplane mode, etc., or install a Battery monitor app and what to look for?. I am using 5.1 stock, I've only unlocked the Bootloader, installed Root and TWRP, everything else is stock. Is there a Custom ROM I can install to optimize Battery without having a huge sacrifice in Performance? thank you very much