my $string  = pack "A*" => map { chr (32 + int rand 95) } 0..1024000;
print length($string);

##</code><code>##

my $string;
$string .= chr(32 + int rand 95) for 0..1024000;

##</code><code>##

            Rate subsingle   subplus      tran
subsingle 18.5/s        --      -15%      -93%
subplus   21.9/s       18%        --      -92%
tran       268/s     1345%     1121%        --