Finally I tried this QEMU setting:
-cpu host,hv-passthrough
What the “hv-passthrough” parameter does is enabling all available hypervisor enlightenments, overriding other hv-* ones if there are.
Results:
Finally a noticeable speed boost.
I tested when installing the ugly updates of Windows’s Patch Tuesday. From the moment of beginning to download updates to finishing rebooting, it took close to 3 hours before; now with this it took 1.5 hours.
Also, VM’s usage felt overall slightly better, more usable indeed.
Still it takes double time compared to bare metal, but probably this is the best one can do with consumer rig…
Oh, and as per QEMU’s documentation, these CPU settings prevent safe VM live migration, but since I don’t need that at least for the time being…
Just posting this in case it’s useful for someone else.