MzScheme/Racket's continuations are of the "copy the C stack" variety, or were last time I checked. They are in no way efficient; it would probably be better t

MzScheme/Racket's continuations are of the "copy the C stack" variety, or were last time I checked. They are in no way efficient; it would probably be better to CPS transform your own code than try to use MzScheme/Racket's continuations directly in performance sensitive code.