Thanks for the pointers. Is LispWorks the only currently-available IDE you'd recommend? The example you've given runs very quickly in Racket; it completes in s

Thanks for the pointers. Is LispWorks the only currently-available IDE you'd recommend? The example you've given runs very quickly in Racket; it completes in some vanishingly small fraction of a second. Perhaps you were running it in DrRacket? If you're interested in any kind of performance in Racket, use the console REPL rather than DrRacket. The IDE instruments the code quite heavily, slowing it down rather a lot. [ETA: For me, on a Linux machine, it takes 13ms in a terminal, and 227ms in DrRacket. I wonder why you were seeing the code run 100x slower than that? Perhaps it's a DrRacket-on-OSX thing.] [ETA 2: There's clearly some buffering going on. Display of the text is the slowest part in DrRacket, and 227ms isn't enough time to plausibly include the text-rendering, so measuring this stuff is basically just hard. The terminal, unsurprisingly, is better at printing text quickly :-) ]