i am also wondering about this and happen to be in the middle of testing some L2 tunneling (etherip mostly, might also test vxlan or egre) with ipsec and wireguard in a set of VM's on virtualbox.

the SMP improvements in the networking stack caught my eye and i am in the process of trying to upgrade these vm's and re-test (iperf3). if i find anything interesting i'll report back