[Q] Best kernel for OPO topic

Hi all I have this amazing device and I'm starting to flash some custom ROMs. Now I mount Paranoid Android 4.4.4 beta6 with franco.kernel r35
My battery life is less than I expect. I can run my screen for about 4/4.30 hours before my OPO shut down. Now I would know if you use another kernel or ROM and how can I improve my battery life. Thank you all for future answers.