pfsense on proxmox high cpu use with ipv6

[GPz1100]

host
Proxmox 8.2.2
5800x cpu
64gb ram

I'm a new pfsense user. Pfsense installed as vm to the above. My isp connection is symmetrical gigabit fiber. Coming from sophos UTM with similar guest configuration as below.

pfsense Guest
4 vcpus
8gb ram
assorted virtio nics and igb in pass through (nics from i340-t4 card)

The proxmox host is supported by a UPS that reports power consumption at 1 watt precision (not necessarily accuracy) with relatively quick update intervals. Tested various combinations of nics for lan/wan, including igb for both, vtnet (virtio) for both, and combinations there of.

Testing consisted using iperf3 on a lan client to test a public iperf3 server capable of saturating my isp link connection.

In general there was higher power consumption with virtio nics in any capacity. This was unfortunate but to be expected ¿?.

What really threw me off was the difference between ipv4 and ipv6 speed tests. In general, there was upwards of 15-20W delta between using ipv4 and ipv6, with the ipv6 consuming more power when using igb for both lan/wan (no virtual nics).

Other than not using ipv6, is there something I can do to optimize it to reduce cpu load.