Simplistic idiomatic Clojure is much faster than JRuby, but often a bit slower than Java and Scala depending on how much you rely on reflection. However, if yo

Simplistic idiomatic Clojure is much faster than JRuby, but often a bit slower than Java and Scala depending on how much you rely on reflection. However, if you push it, Clojure can be as fast as anything else on the JVM; it's just a matter of how much time you spend profiling and optimizing. In many cases you can output the exact same bytecode in Clojure that you'd get from a several-times-more-verbose Java program. An extreme example: http://meshy.org/2009/12/13/widefinder-2-with-clojure.html http://meshy.org/2009/12/13/widefinder-2-with-clojure.html