Kawa predates Clojure by a decade. (Kawa work started 1996; Clojure's initial release was 2007.) Also, Clojure isn't really focused on high performance, while that has always been a priority for Kawa, which generates bytecode similar to Java, especially if you include suitable type annotations. (It is likely Clojure have have improved in this respect - they have a lot more people working on it.)