Your Cfactorial case didn't make real use of a closure. You should take out the "my" in the sub and do 
$iClosure = shift;

[download]
Your benchmark is not fair to Closure because you are repeatedly creating subroutines. The following would be better: 
our $iGlobal;
our $closure_sub = Cfactorial();
timethese (1000000,
{
'Recursion' => 'Rfactorial(30)',
'Global' => 'Gfactorial(30)',
'Lexical' => 'Lfactorial(30)',
'Closure' => '&{$closure_sub}(30)',
}
);

[download]
When I do this I find that the times for Closure, Global, and Lexical are virtually identical.

In reply to Re: Recursion Alternatives? by tall_man
in thread Recursion Alternatives? by Cabrion

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