You're right, that was my plan actually, but I got sidetracked by the cygwin beast, sorry. I timed the fib(36) function from within a clojurescript repl inside

You're right, that was my plan actually, but I got sidetracked by the cygwin beast, sorry. I timed the fib(36) function from within a clojurescript repl inside a clojure jvm repl, and it returned in 86 seconds. Then I timed the generated js function in a Chrome console with a not-so-minor modification so it would compile, it returned in 13 seconds. The modification in question was inlining the generated cljs.core.truth_(predicate) javascript function. The orders of magnitude don't lie though - for what it's worth, a recursive fibonacci implementation in plain java returns in about 125ms (and depending on jvm warm-up, an array-backed computation is a merry jog of 50 to 300µs, but that's completely off-topic) I have yet to setup gambit and clone the clojure-scheme project. I'm really curious though, I like these 800ms that the author advertises.