Custom Kernel or not ?

Well its a simple question, im using Stock (eu) 5.1 optimized rom by Lost101, work so good but its time to flash a custom kernel or not?? I would have more battery performance (I got 6 hours screen now) and a better using ( With 1 gb RAM and using Facebook, Chrome and Instagram when i press botton home , the principal screen appear 1 or 2 second after) with the custom kernel ?

Thanks !!