Proxmox with a FreeBSD guest
Proxmox recommends using ntpd daemon in a FreeBSD client to maintain client real time synchronization. See pve.proxmox. com/wiki/FreeBSD_Guest_Notes and forum.proxmox. com/threads/time-drift-in-windows-7-guest.41268/#post-198848

Real time is set in the guest when it first starts. After which the guest clock drifts with the hosts processor crystal.

ntpd is the ntp daemon. See www.freebsd. org/cgi/man.cgi?query=ntpd&apropos=0&sektion=8&manpath=FreeBSD+12.2-stable&arch=default&format=html

Configured via /etc/ntp.conf

Command line interface ntpq See www.freebsd. org/cgi/man.cgi?query=ntpq&sektion=8&apropos=0&manpath=FreeBSD+12.2-RELEASE+and+Ports

11 minute hardware real time clock update can be enable by adding the line "SYNC_HWCLOCK=yes" to /etc/sysconfig/ntpdate

date gives time of day to 1 second resolution

Qemu guest agent
I think qemu can also sync time between the guest and Porxmox host.

Doing so is suggested github. com/aborche/qemu-guest-agent/blob/master/supported_command_reference.md

Other virtualization systems such as vmware have time synchronization between host and guest via the agent

Time synchronization should be done via only one system otherwise interaction between them decreases time system accuracy. Which mean if an agent and ntpd is used then there would need to be a way of disabling time synchronization via the agent. I'm not sure how to do this.

pfsense guest on Proxmox host
Given it is probably best to run ntp (chrony) on Proxmox then synch time in pfsense to the Proxmox host via ntpd over the LAN interface. Ideally I would like to do the following but not sure how to acheive that in pfsense

Enable ntpd on pfsense but not listening to clients on any interface. Selecting no interfaces in the GUI does the reverse.

Disable hardware real time clock update by pfsense. This is done every 11 minutes by chronyd on the Proxmox host. In pfsense the directory structure is different, so I can't goto to /etc/sysconfig/ntpdate and set SYNC_HWCLOCK=no

And how does ESXi 7.0 install relate to pfSense ?
You ought to do a better 1'st post.

Btw: 7.0 removed the linux subsystem , rendering ALL realtek-drivers useless.

/Bingo

@maverickws

have you checked iperf3 speeds between pfsense and xcp-ng itself?
Mine is bad. Additionally from pfsense to xcp-ng it has many retries during transfer

@wyattwic Yes, qemu is not kvm, however it tends to do all the dirty work, like bios emulation etc and then sends the code to kvm for execution, if there is such option, or emulates it.
It would be interesting to see performance differences between hardware virtualisation and emulation on such a heavy ι/ο related system such as pfsense.

Problem solved. You need to set "Westmere" or "kvm64" CPU type instead of host passthrough in libvirt/virsh/kvm/qemu configuration file "virsh edit $vmname"

<cpu mode='custom' match='exact' check='none'>
<model fallback='allow'>Westmere</model>
<topology sockets='1' cores='6' threads='2'/>
</cpu>