What should I expect in terms of performance running a passthrough GPU in a VM?

[drumstyx]

I've moved all my day-to-day computing to my MacBook Pro that I also use for work. With my desktop, which takes up a considerable amount of space in my office, now largely unused, and in need of a major upgrade anyway (my MacBook has a better GPU...) combined with the steamlink I now have, I was thinking I could just....not have a desktop. My server could run double duty as a gaming machine when I need it, and of course still be my NAS/media server/manager.

What sort of performance can I expect out of this though? When hardware pass-through is supported, is the GPU truly native, with nothing holding it back? CPU-wise, how much sharing is too much? Could I have a quad core CPU, with just a fraction of a core dedicated to Unraid while I'm gaming (scaled on demand, of course)?

Additionally, what if I wanted to use non-steam Remote Desktop for some games? Say something that isn't on steam, and I want to play it on my Mac, does that sort of thing stream alright over gigabit ethernet? Wireless AC?