Is the lua implementation very new and/or incomplete? It seems to be missing from the benchmarks, and if it's lua 5.1, maybe it'll work with luajit?

[ed: Also interesting to note that the clojure version is much slower than scala/java. If nothing else, I guess it's an indication of performance gains that can be had by implementing parts of a clojure program in java (unless there's something off with the clojure implementation, of course.]