apple tv stutters even though it plays flawlessly on my mac

The movie (which is a file on my computer) plays flawlessly and is great quality, but when i connect to the apple TV it begins to stutter and the sound pauses when to match the stuttering video. Again, it plays perfectly on my mac pro, but once i connect it to my apple TV it begins to stutter a lot. I tried messing with the resolutions, with teh exteneded desktop and all that, but it's still very hard to watch. The whole reason I got the apple tv was for me to stream movies from my computer to the apple tv, but if it can't do that, then whats the point? Am i doing something wrong? Is it something to do with the internet? Or with the apple tv? Or even my computer?