Benchmark: timing 1000000000 iterations of ByteSemantic, CharSemantic...
ByteSemantic:  5 wallclock secs ( 4.06 usr + -0.02 sys =  4.05 CPU) @ 247157686.60/s (n=1000000000)
CharSemantic: 10 wallclock secs (11.11 usr +  0.00 sys = 11.11 CPU) @ 90017103.25/s (n=1000000000)
                    Rate CharSemantic ByteSemantic
CharSemantic  90017103/s           --         -64%
ByteSemantic 247157687/s         175%           --

package PayPalNVP; # Name Value Pair API

use strict;
use warnings;
use LWP::UserAgent;
use HTTP::Request::Common qw(POST);
use CGI;
use Data::Dumper;


sub new{
        my $class = shift;
        my %in = (
                USER => 'sdk-three_api1.sdk.com',
                PWD  => 'QFZCWN5HZM8VBG7Q',
                VERSION => '2.3',
                SIGNATURE => 'A-IzJhZZjhg29XQ2qnhapuwxIDzyAZQ92FRP5dqBzVesOkzbdUONzmOU',
                URL => 'https://api-3t.sandbox.paypal.com/nvp',
                @_
        );
        my $self = bless{}, $class;
        return eval{
                $self->{BASE} = \%in;
                $self->{UA} = LWP::UserAgent->new;
                $self;
        };
}

sub test{
        my $self = shift;
        my $req = POST $self->{BASE}{URL},
        Content => [
                USER         => $self->{BASE}{USER},
                PWD          => $self->{BASE}{PWD},
                VERSION      => $self->{BASE}{VERSION},
                SIGNATURE    => $self->{BASE}{SIGNATURE},
                METHOD       => 'SetExpressCheckout',
                AMT          => '10.00',
                CURRENCYCODE => 'EUR',
                RETURNURL    => 'http://example.com',
                CANCELURL    => 'http://example.com',
        ];
        
        my $res = $self->{UA}->request($req); # res = Response

        my $query = CGI->new($res->content);
        # parse name value pairs
        my %h = map{ $_ => $query->param($_)  }$query->param;
        print Dumper \%h;
}

1;##################################################################################################
package main; 

use strict;
use warnings;

my $ppa = PayPalNVP->new or die $@;

$ppa->test;

$VAR1 = {
          'BUILD' => '4181146',
          'CORRELATIONID' => '15b93bef44c34',
          'ACK' => 'Success',
          'TOKEN' => 'EC-1TF74060KX538702V',
          'VERSION' => '2.3',
          'TIMESTAMP' => '2012-12-03T18:37:50Z'
        };