Tornado vs. Phalcon vs. webapp2

By using non-blocking network I/O, Tornado can scale to tens of thousands of open connections, making it ideal for long polling, WebSockets, and other applications that require a long-lived connection to each user.

Phalcon is a web framework implemented as a C extension offering high performance and lower resource consumption.

webapp2 is a simple. it follows the simplicity of webapp, but improves it in some ways: it adds better URI routing and exception handling, a full featured response object and a more flexible dispatching mechanism.