Just had a look at the tests and the urls responded to differ:
Shouldn't all these examples at least be trying to do the same sort of work? For such a trivial test differences like that could make a huge difference to the outcome.
It's great to see replicable tests like this which show their working, but they do need to be testing the same thing. I also think they should have something more substantial to test as well as json marshalling on all the platforms, like serving an HTML page made with a template and with the message, as that'd give a far better indication of speed for tasks web servers typically perform.
Still, it's a great idea and really interesting to see this sort of comparison, even if it could be improved.