With performance engines, regular oil will begin to break down at the higher end of the operating temperature of the engine. Once the chemical bonds in the oil have broken due to this high temperature, their lubricating ability is reduced significantly, causing wear and tear on the engine, and some reduced performance due to friction.
With synthetic oil, it is designed not to break down until much higher temperatures. If you drive your car hard, then synthetic oil will likely save you some on mechanical repairs in the future, but there will likely be only a minimal increase in performance.
The big thing with synthetic oil is that you can't switch back and forth between synthetic and regular all the time. You should choose one type and stick with it (at least that's what my mechanic told me). So if you switch to synthetic be prepared to continue to pay out that extra money for oil over the life of the car.