For your USB situation, I would either buy a PCI USB Controller to pass through, or if your board is able you can check sys-usb’s PCI devices and see how many there are and experiment with what corresponds with which ports. Easiest way to do this for me was to start Qubes with qubes.skip_autostart then I would try one at a time attaching the devices that are attached to sys-usb to the HVM and figure out what set of ports it takes up.
If it seems workable (enough ports for Host/Guest) pass it through to your VM and remove it from sys-usb. I have a powered USB hub with a physical USB switch, then a second unpowered switch just for my USB soundbar so I can keep the audio on the host and switch it only when necessary.
For the rest, I don’t have much help to offer but I am experiencing similar. I have tried passing through my NVMe hoping that it was just the poor I/O with the Xen drivers (though I have not tried installing the host onto this drive yet, just mounting games via it).
CPU Pinning didn’t help (I’m on a 5800X so apparently it isn’t necessary), tried different clock timers (hpet disabled, tsc enabled/native). Tried vcpupin, vcpusched and emulatorpin both with smt enabled and disabled with no real difference. I pinned 0-1 to dom0 and the rest to the HVM and did notice it only loads down the cores I have pinned so seems like it’s working decently though I have not done core isolation.
Performance in-game for me is roughly half, Cinebench I got the same scores as metal for CPU for Single and Multi Core but my GPU score did drop by about 3000 points. Same framerate on the Linux distros, not noticing the CPU maxing out or even coming close to it and watch -n 1 xenpm get-cpufreq-average
does show the cores boosting to ~4.6GHz.
On the host CPU Governor I have set to Performance as well, High Performance power plan in Windows. No virtualization or anything just a bare Win10 with Steam and Cyberpunk and Starfield. Both VMs only show the CPU Frequency as 3.7GHz but from what I can tell this is normal and the cores do actually appear to be boosting.