coolant...?

What type of coolant would be good to use that would cool better than antifreeze since i'm not worried about it freezing at this point and time of the year. I'm having some issues with it cooling. My fan likes to kick on a lot even though its full of fluid. Temp in Alabama is from 95 to 100 right now and I need to keep this thing cool so the heat doesn't rob my engines power. I know this sounds crazy but I've thought about getting a 180 degree termo-stat but i don't want the decrease in MPG. What do I do, anything???? Please help :brickwall