You might be surprised how well the HD 4000 graphics chip does on mid range 3d games. The game I was trying to work on is a mobile game with low poly count and low res textures, and still the editor on Mac had a lot of trouble.
Anyway, the point is, on Mac the editor could barely run with the game loaded. On the Windows machine with very similar specs and the exact same graphics chip the editor works fine… maybe 10 times faster than the Mac version.