Switched back to kvm and host-passthrough vm defaults. This will break Virtualbox, but it will make machines on bare metal and kvm setups run a lot, lot faster.

snap-overlay/etc/nova/nova.conf.d/hypervisor.conf

@@ -5,5 +5,5 @@ compute_driver = libvirt.LibvirtDriver
 disable_rootwrap = True
 
 [libvirt]
-virt_type = qemu
-cpu_mode = host-model
+virt_type = kvm
+cpu_mode = host-passthrough