I've had good results using CHI but I'd also first look at Hippo's suggestion of solutions in the DB - almost all of them allow either pinning tables to memory or using an in-memory engine. You can even put the backend DB's on a RAM Drive, but if you're not interested in solving this at the persistence layer then I'd suggest looking at CHI as well as the other suggestions.

CHI has been around a long time and although it hasn't seen much updating recently it's proven in many production environments - there's also some interest in porting it to Perl6 which I assume is a good thing.