The single sentence that surprised me the most:
"For performance, there is no question that Haskell will win hands down on any performance comparison".
"For performance, there is no question that Haskell will win hands down on any performance comparison".
Haskell is a compiled language with a very clever optimizing compiler, so it tends to be pretty fast by any standard. On top of this, it has recently had some improvements to its IO manager which is particularly important for web servers.
Ruby, on the other hand, is notoriously slow.
The Warp web server for Haskell is the fastest Web application server that exists. http://steve.vinoski.net/pdf/IC-Warp_a_Haskell_Web_Server.pd... [pdf, but easy to read] -- in the comparison on page 2, php handled 3400 requests per second, and Warp 81000.
As to why, here is a hint: The three most common webservers in the world are Apache, nginx and IIS. Yet are any of those even mentioned in that paper? NO.
However I suspect that the three you listed would not be benchmarked on their own, as they are not application servers, just frontends. It would be more reasonable to benchmark Apache+mod_wsgi or whatever, and it would be nice to see that on the graph.