I've used (and still am using) Lucy for many years since the KinoSearch days and can testify that it's one of the gems on CPAN. At least since it's rename to Lucy it's stable and perfectly production ready. Getting it to work is a bit tedious, as you have to fine tune / design every bit of your application, but once it's working, it's fast and consistently performant. I never did benchmarks, but I had a multi-million docs project once where many components had difficulties, except Lucy, which plowed through like a champ.