Sure wish my JVM started in 40ms. Here's ruby:

    $ time ruby -e "puts 'hello world'"
    > hello world
    >
    > real	0m0.076s
    > user	0m0.029s
    > sys	0m0.017s

And here's jruby:

    $ time ruby -e "puts 'hello world'"
    > hello world
    >
    > real	0m1.161s
    > user	0m2.050s
    > sys	0m0.093s

Your JVM does. jruby.jar is megabytes of reimplementation and mapping of the Ruby stdlib onto the JVM. Plus in this example, loading a Ruby parser and interpreter.

Here's executing an assembly (über-jar) I wrote in Scala:

  → time scripts/couch 
  Please provide a basePath and a valid command. ("backup", "restore", "truncate", "migrate" or "migrate-all")

  real	0m0.375s
  user	0m0.415s
  sys	0m0.073s

That's basically just `java -jar couch-utils.jar`.

A few hundred ms on my 1.2GHz MacBook. And this includes a bunch of Akka Actors.

That rather proves the opposite: 6s Clojure startup time, for reasons that aren't obvious enough to be included in that blog post.

But its neither a Java nor JVM problem.