Probably because the guys and gals at Apache recognise the importance of performance, and take the time to optimise their code.
As distinct from the wider perl community, if most of those around this site are anything to go by, who don't bother to. After all, "hardware is cheap!".
They don't seem to realise the damage it causes to the Perl's reputation when potential commercials users put together a POC using half a dozen CPAN modules, each of which is profligate with both time and memory, and run it along side a similar app written in Java, and waddaya know. The perl app runs 10 times slower.
So optimise it!
Ah, but the culprits are the layers of standard and cpan modules that we cannot modify because its standard co. policy not to modify 3rd party software. Perl's rep takes another hit, and Java gets the gravy.