About battery drain, try to use AccuBattery app to see your real battery health and how much u have screen on and screen off battery drain. Is your battery OEM one or Lehehe? Much battery sold on Aliexpress are fake, max 2000 mah real capacity.
Gallery lag happens on other roms also. I am using superioros q and that lag is gone. On msm xtended there was lag also, didnt matter which gallery app...
Well I installed AccuBattery and it appears I've been swindled... Accubattery estimates that the real capacity of the battery is 2155 mAh. So much for buying a new battery... Damn.
Well it's good news for the rom at least!