This has actually changed. A friend of mine plays all modern games with sometimes even better FPS using the PCI passthrough in QEMU[1], I have to say it's a pretty impressive setup and I've played Witcher 3 with Arch Linux + QEMU + Windows 7, solid 60fps with ultra graphics.

[1] https://wiki.archlinux.org/index.php/PCI_passthrough_via_OVM...