Oneofakind Marshmallow custom rom for Xperia S is based on AOSP and it is focused on battery conservation, performance and stability. It is very lightweight rom that offers a smooth scrolling experience on your device. Besides, it is a packed with a whole lot of other features that you're gonna love.
This rom is already rooted, so you need not worry about rooting your LT26i after flashing the rom.
How To Flash Oneofakind Marshmallow rom on Xperia S