I've recently converted some code here to XS (from just ordinary C programs called via backticks).
It's no faster than the backticks version, and I can't for the life of me figure out why. Conventional wisdom tells me the fork/exec cycle of a backtick should be significantly slower. I mean I know fork on Linux (2.4.6, fwiw) is supposed to be fast, but...
Anyhow, I've posted this to clp.moderated, so if you have any thoughts on this, answer there (once it passes moderation).