The biggest bangs for the buck:
- pre-loading modules in startup.pl and not scribbling on shared data - reduces both memory usage and response time by up to 30% each
- Correct database schema - reduces SQL query response time by up to 90%
- Usage of CPAN modules - reduces response time by up to 30%
Those numbers are cumulative. I've seen a report go from 270 seconds to 3 seconds, just by following those three items.
- In general, if you think something isn't in Perl, try it out, because it usually is. :-)
- "What is the sound of Perl? Is it not the sound of a wall that people have stopped banging their heads against?"