use Benchmark;

$a = shift;
$b = shift;
print "A = $a\tB = $b\n";
$hash{$_}  = $_ for (1..$b);
@array[$_] = $_ for (1..$b);

sub doSubR { ${$_[0]} = ${$_[0]}}
sub doSubV { return $_[0]       }

timethese ( $a, {
  '1 Nothing  ' => 'for (1..$b) { $trash = $_               };',
  '2 Mult     ' => 'for (1..$b) { $trash = $_ * $_          };',
  '3 Array    ' => 'for (1..$b) { $trash = $array[$_]       };',
  '4 Hash     ' => 'for (1..$b) { $trash = $hash{"$_"}      };',
  '5 Sub (Ref)' => 'for (1..$b) { doSubR(\$_); $trash = $_  };',
  '6 Sub (Val)' => 'for (1..$b) { $trash = doSubV($_)       };',
});

##</code><code>##

[lexicon]$ perl bench.pl 10 1000000
A = 10  B = 1000000
Benchmark: timing 10 iterations of 1 Nothing  , 2 Square   , 3 Array    , 4 Hash     , 5 Sub (Ref), 6 Sub (Val)...
1 Nothing  : 35 wallclock secs (29.99 usr +  0.10 sys = 30.09 CPU)
2 Square   : 58 wallclock secs (48.79 usr +  0.23 sys = 49.02 CPU)
3 Array    : 63 wallclock secs (54.49 usr +  0.20 sys = 54.69 CPU)
4 Hash     : 184 wallclock secs (156.99 usr +  0.60 sys = 157.59 CPU)
5 Sub (Ref): 388 wallclock secs (327.87 usr +  1.30 sys = 329.17 CPU)
6 Sub (Val): 312 wallclock secs (266.54 usr +  1.02 sys = 267.56 CPU)

##</code><code>##

Function  Time(S)   Relative
Mult:     19        01.00
Array:    24        01.25
Hash:     127       06.68
Sub (R):  299       15.70
Sub (V):  237       12.47