Wow, my mac isn't as fast as that and it renders faster than what you're saying. But what Nancy says about Mac rendering slower is both true and not true. I've noticed that things like basic procedurals and materials render considerably slower on a mac, however, effects like Particles, Lens Flares etc render considerably faster than windows do. I've had a shot that had an intense particle effect, would take almost 2 minutes to render on windows, about 10 seconds on a mac. It was crazy.