[Q] Samsung grand duos battery issues topic

Hi sir/mam I have a samsung galaxy duos running android version 4.2 im having trouble of the slowness of my phone , so I search on the internet of some tips to make my phone better so I found out that galaxy duos had a issue or problem on android version 4.2 so I had to downgrade my phone to make my phone better based on what ive seen on the net. So after I successfully downgrade my phone using firmware from Taiwan ny phone is faster now . App runs smoothly but I noticed that my battery life is now draining faster than before . Now I wanna know if this is due to firmware from taiwan? Second is there any method to improve my battery life? Or do I need to install other countries firmware? Btw im from Philippines, ai did not install firmware from ph bec of the carriers lock.