Thanks for letting us know about this. We've been receiving other reports about problems with Mac and Linux builds, so I've decided to pull them down for the time being. But if you'd like to help us with testing, we'd be glad to have you.
That said, what you're describing sounds like an issue we have with all Mac laptops. I have one too, and I wouldn't ever try to play an unfinished indie game on it, or much else for that matter. For us, often the way they handle graphics just slows the game down a ridiculous amount. I'm going to see what I can do about it, though.