alt Hacker News> I get 40 Gbit/s over a single localhost TCP stream on my 10 years old laptop with iperf3.
Do you mean literally just streaming data from one process to another on the same machine, without that data ever actually transiting a real network link? There's so many caveats to that test that it's basically worthless for evaluating what could happen on a real network.
Yes. Why?
To measure other overhead of what's claimed (TCP the protocol being slow), one should exclude other things that necessarily affect alternative protocols as well (e.g. latency) as much as possible, which is what this does.