#!/usr/bin/perl

use strict;
use warnings;

$SIG{CHLD} = 'IGNORE';

if (fork()) {
    print "Content-type: text/html\n\n";
    print "ok";
    exit;
}

close(STDIN);
close(STDOUT);
close(STDERR);

#start doing lots of things that are time consuming
blah1();
blah2();
...