A 6x performance gain when going from Perl to Java sounds awfully suspicious. There has to be more to the story.

Is there any chance that your colleague's site was a vanilla CGI application rather than a mod_perl or FastCGI app? (I'm assuming this is a web-based app) If so, those numbers might quite reasonable, but the joke's still on them.

Were there optimizations that occurred to the database(s) in the meantime? Like new/improved indexes or stored procedures? Talented DBA work can offer stunning performance increases.

I'll be the first to admit (possibly wrongly) that Java has a performance edge over Perl, when both are given equal luvin' and skill, but NOT 6x, probably not even quite 2x. And I say this a someone who is experienced w/both languages. Perl is the apple of my eye because it takes ALOT less effort to write and maintain.