do some overclocking.... but be cautious..
try system tuner
all you need is there to reduce a big amount of lag ... you can study it by yourself and some little search
a cache cleaner app also help to reduce lag...
and mostly why people root their devices because of custom roms and kernels,
so try finding the perfect combination of custom rom and kernel depending on your device.
im just tryin' to help, so i hope it helps