Yes, it's "crap" not because GPU is slow but rather that most triple A title games are optimized for Windows. So it's difficult to expect a good performance from a game that runs with API conversion layer(s) (Windows -> Mac) and then CPU emulation (x86 -> arm).

So publishers/developers need to make more native games. Even though every Mac port will probably make 1/10th revenue of a Windows title I guess Mac users would be happy to pay more for better games. I certainly would.