If you have a home lab, offshore what you can from your firewall. The less it does the more secure it is. Once you've watered it down to maybe DHCP and suricata then there's almost no difference in pfsense and opn.

Have you tried iperf from the vm to another physical machine on the network? Since iperf uses ram there may be some funky resource management happening between VMware and windows 11 with that much RAM activity happening at the same time. You may also want to disable any dynamic ram settings and make it as static as possible.