@mint @feld Yeah, I forgot who said it but really early on, I remarked that Phoenix couldn't keep up and was chewing CPU because if Elixir is going to be some immutable stateless deal that it needs to have a call for IO.copy(fd1,fd2) *somewhere*, and I got an objection from one of the devs, I forget who, but there's not really a way around it: there's one way to get data out of one FD and into another efficiently and in a pure-ish functional language you have to just write some C and wrap it in something that fits the language's semantics, because it's a fundamentally FP-unfriendly task. @j probably remembers this because we both came to the same conclusion around the same time and we traded notes on nginx configuration.