Since a couple of months processing incoming IP packets on OpenBSD no longer requires the KERNEL_LOCK(). The first consequence is an improved latency of the system but apparently it also made packet forwarding 20% faster.

At least that's what Hrvoje Popovski measured by the time of the commit, and more recently on his Xeon box (E5-2643 v2 @ 3.50GHz, 3500.44 MHz). When he performed some tests for the vlan(4) regression, he measured on his machine a throughput of 1.42Mpps. Last week, with a -current kernel he measured a throughput of 1.75Mpps.

Yes, it is a bit more than 20%. Yes, the stack is still mostly single-threaded.