Back in August 2004, I wrote a piece comparing Perl and Java regex performance, observing that, to my surprise, apparently Java was way faster on what I thought was a pretty common task. Last month, Ben Tilly wrote me saying that Perl consciously accepted a regex slowdown to route around a pathological case where search time could explode to infinity. I asked him to write it up and promised to point to it, and he has. If you care about this kind of thing, read Ben’s piece and don’t miss the comments, which are interesting. Summary: the jury’s still out. See also: Open-Source Regex.