I don't think any games rely on more than a few dozen megabits of Internet bandwidth at a few hundred packets per second. And that netfilter/iptables NAT on a X

I don't think any games rely on more than a few dozen megabits of Internet bandwidth at a few hundred packets per second. And that netfilter/iptables NAT on a Xeon is not gonna add more latency than the equivalent netfilter/iptables NAT that runs on a typical ARM/MIPS home gateway/router.