Benchmark::cmpthese(5000, {
   'outside' => sub { 
         my $x; my $y; my @z; my $i; 
         for ($i = 0; $i < 1000; $i++) {
            $x = $i;
            $y = $x;
            @z = ($x, $y)
         }
            },
   'inside' => sub {
            for (my $i=0; $i < 1000; $i++) {
               my $x = $i; 
               my $y = $x; 
               my @z = ($x, $y)}
            }
});

         Rate  inside outside
inside  120/s      --    -13%
outside 138/s     15%      --

##</code><code>##

for(my $i = 64; $i < (scalar(@rddt) - (2 * $pond)); $i++){

##</code><code>##

@rddt = (1) x 1000;
$pond = 32;

Benchmark::cmpthese(500, {
   'inside' => sub { 
            for ( my $i = 64 ; $i < ( scalar(@rddt) - ( 2 * $pond ) ) ; $i++ ) {
               $x++;
            }
               },

   'outside' => sub {
            $limit = scalar(@rddt) - ( 2 * $pond );
            for ( my $i = 64 ; $i <  $limit ; $i++ ) {
               $x++;
            }
               },
});

inside  273/s      --    -39%
outside 450/s     65%      --