I don't know how much this will help your specific situation, but you'll generally see an improvement if you write Perl like Perl, not as a dynamically-typed C.

The thing that immediately stands out to me is the use of the three-arg form of the for loop in Perl. This is basically there for the benifit of old C programmers. Personally, I see it used so seldom Perl that I often forget it exists.

The Perl-ism is something like this:

# Change this: 
for($num=0;$num<16777216;$num++)
# To this: 
for my $num (0 .. 16777216)

# And this: 
for($i=1;$i<=24;$i++) 
# Becomes this: 
for my $i (1 .. 24)
[download]

Using more Perl-ish constructs often provides hints to the optimizer, as well as generally reducing code size without hurting maintainability.

A few other ideas that may or may not help:

• Lexical scoping. See Lexical scoping like a fox.
• Put a use int; at the top. By default, Perl will use floats in arithmetic, which will slow you down. use int; forces it to use integers.

----
I wanted to explore how Perl's closures can be manipulated, and ended up creating an object system by accident.
-- Schemer

Note: All code is untested, unless otherwise stated