Peter Funk:
The performance in Qubes-OS was not as good as in Ubuntu. I had to
change "smt=off" to "sched-gran=core smt=on" in order to enable
hyper threading. That was first possible with Qubes 4.1.0. In
Qubes 4.0.4 hyper threading was disabled.
You're probably aware, but Smt=off is the default for security reasons, I believe.