One issue I've seen from a fair number of people on the APU2s running FreeBSD is if they've got PPPoE; inbound traffic (at least) all hashes to the same RX queue, and as a result there's no parallelism... if you're on gigE fiber with PPPoE, the APU2 can't really keep up single threaded. The earlier APU (1) boards use realtek nics that I think only have a single queue, so you won't get effective parallelism there either. If I'm finding the right information, APU2s with i210 have 4 rx queues which is well matched with a quad core, but those with i211 only have 2 rx queues, which means half of the processors will have nothing to do unless your kernel redistributes packets after rxing, but that comes at a cost too.

Linux may have a different packet flow, or netfilter could be faster than pf.

> I find nftables to be frankly less challenging than pf

I also don't really care for how pf specifies rules. I would rather run ipfw, but pf has pfsync whereas ipfw doesn't have a way to do failover with state synchronization for stateful firewalls/NAT. So I figured out how to express my rules in pf.conf; because it was worth it, even if I don't like it :P