#! /usr/bin/perl
use warnings;
use strict;

my $max = shift;
my @primes = (2);
my $i = 3;

while ($i <= $max) {
    my $sqrt = sqrt $i;
    for my $num (@primes) {
        last if ($i % $num == 0);
        push @primes, $i and last if $num > $sqrt;
    }
    $i += 2;
}
print "1, @primes";

##</code><code>##

real    0m37.682s
user    0m37.296s
sys     0m0.015s

##</code><code>##

real    0m4.035s
user    0m3.531s
sys     0m0.062s