There is a good chance that your box is slower due to the fact that you're on a mobile chipset and there are various factors involved such as speed stepping, when you're on battery power, etc. You're also a little over 1GHz slower than most i7 desktop processors.
My 15" Retina (16GB RAM/256GB SSD) doesn't have an nvidia graphics card in it either and while that does not matter with regards to Handmade Hero since we are software rendering, it does reduce the performance of OSX relative to someone else running a peripheral graphics card. That in turn does have an effect on compilation time, especially when you account for Parallels running a Windows virtual machine on top of all that to get Visual Studio up and running.