In addition to the other comments, I will add that this is only viable in languages that are much slower than C. If you take Haskell, Ocaml, Go, Java, C#, Commo

In addition to the other comments, I will add that this is only viable in languages that are much slower than C. If you take Haskell, Ocaml, Go, Java, C#, Common Lisp, Factor and so forth, the speed increase is much lower since these languages are fast by themselves. Thus, the barrier of having to rewrite and maintain a C-implementation at the side is as high, and there is no fruit-tree on the other side of the barrier you can reap. Languages in which CPU-intensive work is fairly expensive are the ones which benefits the most from a C-rewrite. Ruby is notoriously slow in that regard, which makes it a prime candidate for such a rewrite. And before people scold me: Synthetic benchmarks, like the alioth shootout: http://shootout.alioth.debian.org/u64/which-programming-languages-are-fastest.php http://shootout.alioth.debian.org/u64/which-programming-lang... is a good indicator of exactly the CPU-intensive power of a given language. Note however, that CPU-usage is not all constraints of a modern program. Which is, as an aside, why Ruby and PHP are viable options for writing code in.