Benchmark: running Regex, Substr, Unpack, each for at least 3 CPU seconds...
     Regex:  2 wallclock secs ( 3.17 usr +  0.00 sys =  3.17 CPU) @ 42172.56/s (n=133687)
    Substr:  2 wallclock secs ( 3.12 usr +  0.00 sys =  3.12 CPU) @ 56391.35/s (n=175941)
    Unpack:  2 wallclock secs ( 3.16 usr +  0.00 sys =  3.16 CPU) @ 61831.65/s (n=195388)

##</code><code>##

#!/usr/bin/perl -w
use strict;
use Benchmark;

my $input = 'X' x 65;  #test input
my @result;

timethese(0, {
   'Regex' => sub {
                   undef @result;
                   @result = ($input =~ /(.{16})(.{20})(.{20})(.{1})(.{8})/);
                   #    print join "\t", @result;
                  },
   'Unpack' => sub {
                   undef @result;
                   @result = unpack "A16A20A20AA8",$input;
                   #    print join "\t", @result;
               },
   'Substr' => sub {
                   undef @result;
                   @result=((substr $input,0,15),
                                (substr $input,15,20),
                                (substr $input,35,20),
                                (substr $input,55,1),
                                (substr $input,56,8));
                   #    print join "\t", @result;
               },
});