Looking at https://github.com/ericmoritz/wsdemo it seems
he's using his own erlang ws implementation and using a third party library for all the others?
If this is correct, then it's no big surprise that he
does well in his own benchmark that he's developing against.
No. He is using Cowboy[1], which is the mainstream websocket Erlang implementation (uh.. cowboy actually is a socket acceptor pool which happens to have awesome HTTP and WS handlers).
If this is correct, then it's no big surprise that he does well in his own benchmark that he's developing against.