Why is the Clojure Hello World program so slow compared to Java and Python?

Question

Update

As suggested by many people, it looks like this was because of the fact that clojure code was first compiled and then executed. AOT compilation s

Answer 1

To add to dnolen's answer, when doing Python vs Clojure timing contents, you might want to package your "basic unit of work" as a function and then use the time macro (in Clojure) or the timeit.timeit function (in Python; or, better yet, use the timing facilities of IPython) at the REPL. The results should be roughly comparable. (Note that Clojure code needs to be "warmed up" by running it a few times to achieve full performance.)

There are also some benchmarking suites for Clojure, for example Criterium; you might want to consider using one of them.