Tim Bunce points me to this post about Perl being faster than Ruby in Tim Bray's Wide Finder code competition.
The Wide Finder is at heart an Apache log analysis tool to show commonly hit pages, but for purposes of this comparison, it's analyzing 971MB. Bray explains:
It's a classic example of the culture, born in Awk, perfected in Perl, of getting useful work done by combining regular expressions and hash tables. I want to figure out how to write an equivalent program that runs fast on modern CPUs with low clock rates but many cores; this is the Wide Finder project.
All the talk about Erlang and parallelism makes me want to get back to working through my copy of Programming Erlang. Oh tuits, come to me!