use strict;

use Benchmark 'cmpthese';

my $limit = @ARGV ? shift : 100;

cmpthese(-10, {
	recurse => sub { rec($limit) },
	iterate => sub { itr($limit) },
});

sub rec {
  my $n = shift;
  return $n == 1 ? return 1 : $n * rec($n - 1);
}
sub itr {
	my($n, $r) = (shift, 1);
	$r *= $n-- while $n > 1;
	return $r;
}

__output__

Benchmark: running iterate, recurse for at least 10 CPU seconds...
   iterate: 11 wallclock secs (10.58 usr +  0.00 sys = 10.58 CPU) @ 5814.45/s (n=61546)
   recurse: 11 wallclock secs (10.23 usr +  0.00 sys = 10.23 CPU) @ 1677.45/s (n=17162)
          Rate recurse iterate
recurse 1677/s      --    -71%
iterate 5814/s    247%      --