C:\Users\Andy\Documents>perl test.pl
    Length of string: 101000000
    Time taken was  0 wallclock secs ( 0.17 usr  0.03 sys +  0.00 cusr  0.00 csys =
     0.20 CPU) seconds

    Time taken was  1 wallclock secs ( 1.13 usr  0.03 sys +  0.00 cusr  0.00 csys =
     1.16 CPU) seconds
    C:\Users\Andy\Documents>

##</code><code>##

    my $new_string = testing_string($string);

    sub testing_string {
        my $content = $_[0];
        # do some stuff
        $content =~ s/a/b/sg;
        return $content;
    }

##</code><code>##

    # do stuff here
    my %test_var;
    $test_var{$string} = $string;
    testing_string();
    $string = $test_var{$string};

    sub testing_string_2 {
        # do some stuff here
        $test_var{$string} =~ s/a/b/sg;  
    }