pfSense on Hyper-V does 330 MB/s routing

Bob.Dig

I am running pfSense in my homelab on Hyper-V for a long time and never watched to close about the speed other than for internet. But lately I did and noticed that my pfSense VM will only do around 330 MB/s from a Windows VM to the host.
If I do the same on an "Internal Switch" without pfSense, that works with 1GB/s.
Are there any tweaks for pfSense or Hyper-V to speed up things?

Here is a screenshot when copying a file.

Host and Windows VM are connected via pfSense VM on an "Internal Switch", no physical NIC in the mix.