[racket] a small itch regarding flonums

Hi list,

Let me first say that Racket is really great, and that I like it a lot.
However, the other day I found something which made me wonder.

fl+ , fl* etc. in racket/flonum take only 2 arguments,
while fl+ etc. in rnrs/arithmetic/flonums-6 take an
arbitrary number of arguments, just like +.

Why this difference? It looks like the r6rs fl+ gets open-coded
with some macro wizardry so there shouldn't be a performance penalty, right?

Let me be the first to admit that it is not world-shocking,
but nevertheless I would be interested in the rationale.

Thanks,

Stephan