If by efficiency you mean speed the simple fact is that you spend memry to get more speed. Accessing a DB (on disk) is slow compared to accessing data in memory. You can spend memory in two ways. Give your DB huge ammounts of memory to cache disk pages and indices (so it does not have to hit the disks as often) or simply pull all the data you need into memory one pass. With RAM priced at a few hundred bucks a GB and programmer time to code a more memory efficient solution at a similar level per day there is a very good business case for throwing lots more memory at a problem to save code complexity and thus programmer time and debugging time and future maintenance issues.

Perl loves lots of memory. So do RDBMS. If you are doing much work with either a small investment on more RAM has long term wide ranging benefits.