What is the best Scheme or LISP implementation for OS X?

Question

I am looking for a version of Scheme or even LISP that I can use to recover some lost Lisp development skills. Some web capabilities would be nice but not essential.

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Answer 1

I did quite a bit of experimenting with this.

Clozure Common Lisp (née Open MCL) is by far the fastest; 25-30 percent faster than the next competitor on my intel Mac Mini.

MIT Scheme works quite nicely on a Mac. I think I eventually compiled it myself, but there are binaries at that site. PLT Scheme is also nice, and possibly a little better integrated into the Mac world. (PLT Scheme is now known as Racket, but I haven't experimented with it after the change.)