Walkingrandomly.com has a post on the Julia computer language which seems to be getting faster. Carl and I have stumbled across many languages in our efforts to get a fast version of lisp with good debugging tools. For a while we thought at one time that Haskell was the answer, but it now seems we are leaning more toward Clojure and Python recently. It is hard to pass up languages that can use tools like WEKA, SciPy, and Numpy. Another option is R, but only one of my friends uses R. Clojure is neat because it runs on the JVM and Javascript (and is being targeted at other languages such as Python, Scheme, and C).
For a speed comparison with Matlab, see this post.