My host is an EVGA FTW-K X299 + i7-7820X with a Radeon 580 RX in the primary x16 slot and a Nvidia GTX 1080 Ti in the secondary x8 (CPU, not PCH) slot running unRAID 6.8.2.
My client is Windows 10 Enterprise with the Nvidia card passed through (both audio and video) and 4 [real] cores passed through. The VM's configuration is attached, though apparently Windows tacked on a .txt extension...
The computer runs fine. I'm running 4k@60Hz to a Samsung TV, and everything is responsive. There are no color/pixel aberrations, no choppiness, etc; when I move the mouse around, move windows around, type, scroll in the web, everything works wonderfully.
I ran the benchmark from userbenchmark and got slightly slower RAM performance but nearly identical 4-core CPU performance and GPU performance as this same computer gets bare-metal (but with the 1080 Ti in the primary x16 slot). Clearly something is working right (though, interestingly, this computer seems to generally be slower than expected - the GPU isn't performing as well as this card is expected to, but the key is that it's the same as the bare-metal computer, and I played Borderlands 3 at 4k on very high settings with only minor degredation, let alone streaming a video).
If I open a game... Like Portal 2 (let alone Borderlands 3)... or if I play a video on YouTube, I get horribly choppy video (probably 2 fps) and stuttery/choppy audio. This happens whether it's full-screen or a small window, and happens to all audio, and it doesn't matter if it's in Chrome or a video from a local network server played with Windows media player, or if it's a system alert sound, whether it's HD or SD, etc - they're all... slow. Here's a good video shot at a bad angle of the behavior.
Why is this an issue? I have no idea what is causing this and why it's so limited to video playbacks.
VMConfig.xml.txt