Bingo!
Disabling tso/lro fixed iperf performance from/to the opnsense guest. It didn't much for forwarding performance (vm->opnsense->vm) however. But this is a different ballgame.
Disabling tso/lro fixed iperf performance from/to the opnsense guest. It didn't much for forwarding performance (vm->opnsense->vm) however. But this is a different ballgame.