Profile the code and understand the performances from autobahn testsuite's results

[Lawouach]

When going through results, I can see that ws4py doesn't do as well as autobahn performance wise.

http://www.defuze.org/oss/ws4py/testreports/servers/0.3.4/

It happens mainly on large messages so it's unlikely to be a problem for most use cases. Still it would be good to profile ws4py to understand what's going on.

[methane]

@Lawouach FWIW, wsaccel accelerate ws4py performance for large message.