You will be paying cpu 'tax' by running in a virtual machine.
FL has a Mac port, or at least a beta of one, but it is not perfect last I knew.
Also, a Mac will cost you about double what a home-built PC will, and not be exactly what you want.
Do a lot of research, and then get the most monstrous PC you can possibly afford, whether you build it yourself or not.
Thats seriously the best advice, unless money is not a concern.