Benchmark

#!/usr/bin/perl 
use Benchmark; 
timethese(100, 
   { 
      'local'=>q 
            { 
               for(1..10000) 
               { 
                  local $a=$_; 
                  $a *= 2; 
               } 
            }, 

      'my'=>q 
         { 
            for(1..10000) 
            { 
               my $a=$_; 
               $a *= 2; 
            } 
         } 
});