Rooting in itself will not change the way your phone operates. It is the custom ROMs that rooting gives you the ability to install that will increase your performance. Granted, there are many ROMs to choose from, and not every ROM is suited to every individual, but you most likely will experience noticibly faster performance and better battery life with whichever ROM you choose.
Above all, if you decide to root and install a cutom ROM, be sure to follow any and all directions the developer provides for what you're doing. Every device, rooting method, and ROM are unique. The developer has a good reason for you to do something a certain way.