Um, I hate to break it to you, but perl is fully interpreted with no just-in-time compilation. Every operation and every argument passed to it in a script is dozens of branches, no matter how innocent. The way to optimize a perl program is to code it with the fewest possible operations, fewest function calls, fewest assignments to a temporary variable, and even fewest curly-brace scopes. Optimizing a perl program is generally the opposite of making it more readable. (but there is a time and a place, etc)

For a little mind-bender, try this:

perl -MBenchmark -E '
  my $x= 1;
  timethese(50000000, {
    mul => q{$x*$x},
    sqrt => q{sqrt($x)}
  })'
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