You can definitely build an x86 system to route 40Gb/s with small packets for under $3k and it's been the case for many years. A Xeon-D can hit 100gbps forwarding and filtering.

OpenBSD is going through a slow fine grained locking transformation that FreeBSD started over 20 years ago. Eventually they will figure out they need something like epoch reclaimation, hazard pointers, or rcu.