There are at least 2 better http servers for Python, uWSGI and gEvent. Tornado is known to be slower: http://nichol.as/benchmark-of-python-web-servers . More specifically, uWSGI has been shown to respond at under 25ms with 15k+ concurrent connections.

Throw uWSGI behind Nginx (with it's new websocket support), tune it a bit, and I wouldn't be surprised to see it "pass" and perhaps even be competitive.