The way an interpreter is implemented and the language it runs on don't have anything to do with each other.
A Clojure interpreter written in C, if written the same way as for Java, it would run just as slow, given the way it is building Clojure every time the application starts.
A Clojure interpreter written in C, if written the same way as for Java, it would run just as slow, given the way it is building Clojure every time the application starts.