I haven't looked into Racket-math, but this post: http://lists.racket-lang.org/users/archive/2013-January/0560... makes me wonder if Racket is really up for non-toy numerics.

In contrast, SBCL uses tagless float arrays, so that array operations tend to be cache friendly. With adequate declarations, numerical code in SBCL tends to very fast (~1-3x C speed). I assume one can do the same with Bigloo and Chicken scheme as well.