Not to be a wise ass, but because I'm genuinely curious: who cares how fast it is? How often are you regenerating pages? Or is it a factor because of the change-make-check-change-again cycle?
It matters if it takes more than a short while to post your stuff. Jekyll/Octopress would take 20 minutes or so to regenerate my not all that large blog, I imagine that with 1000's of pages it would be unworkably slow.