It is clojure. Clojure literally bootstraps itself on every startup, and this bootstrap takes a little less than a second even on a fully started jvm. And since none of your clojure code can run until clojure.jar is fully bootstrapped, large clojure projects can easily start up for 5+ seconds before executing a single piece of code.

I love clojure as a language, but my code is usually cli oriented and it was such a terrible fit for it that I switched to Scala. Despite being on the jvm, my startup times are an order of magnitude better.