I don’t recall doing any registry edits. Most of the perf work i remember doing was on the VM side - getting the little tweaks in libvirt settings, matching vCPU topology to physical, keeping VM cores from running linux system processes with GRUB flags, using a dedicated USB controller and sound card. i think i set the MSI stuff gnif mentioned as well though it wasn’t critical for me. Generally stuttering will be resolved by making sure time critical events (like interrupts) are delivered quickly to the guest.

+1 on the writing stuff down :D I did it twice and documented pretty thoroughly the second time around, notes before each change, testing performance delta, notes about if it worked. It really helps.

Likely setting the NVidia drivers to use MSI (Message Signalled Interrupts)

I fixed my stuttering by enabling cpu tuning and setting the correct cpu topology [1].

[1] https://wiki.archlinux.org/title/PCI_passthrough_via_OVMF#CP...

I have a VFIO setup as well, and I'm not aware of any register setting correcting stuttering.

There was an issue with AMD systems a few years ago, which caused microstuttering.