Parallel::ForkManager is only sleeping during " $pm->wait_all_children; ", correct? Or are you saying during every fork there is a hard-limit sleep?

Read http://search.cpan.org/~yanick/Parallel-ForkManager-1.17/lib/Parallel/ForkManager.pm#BLOCKING_CALLS and then try this to see if it helps:

#!/usr/local/bin/perl
use strict;
use warnings;
use Parallel::ForkManager;

my $pm = new Parallel::ForkManager(24);
$pm->set_waitpid_blocking_sleep(0);
...
[download]

Thanks for the help, I was able to shave 15 seconds off my perl script with both suggestions.