$ cat 639358.pl
use strict;
use warnings;

use Date::Calc qw(Delta_YMDHMS);
use Date::Manip;
use Date::Parse;
use DateTime;
use Benchmark qw(cmpthese);

my ($d1, $d2) = ("Aug 26 23:10:59", "Aug 27 10:59:02");

sub date_manip {
  return UnixDate($d1, "%s") - UnixDate($d2, "%s");
}

sub date_calc {
  return Delta_YMDHMS(2007, 8, 26, 23, 10, 59, 2007, 8, 27, 10, 59, 02);
}

sub date_parse {
  return str2time($d1) - str2time($d2);
}

sub datetime {
  return DateTime->new(
    year   => 2007,
    month  => 8,
    day    => 26,
    hour   => 23,
    minute => 10,
    second => 59
    ) - DateTime->new(
    year   => 2007,
    month  => 8,
    day    => 27,
    hour   => 10,
    minute => 59,
    second => 02
    );
}

cmpthese(
  -1,
  {
    date_manip => \&date_manip,
    date_parse => \&date_parse,
    date_calc  => \&date_calc,
    datetime   => \&datetime
  }
);

__END__

$ perl  639358.pl
               Rate date_manip   datetime date_parse  date_calc
date_manip    310/s         --       -65%       -89%      -100%
datetime      888/s       186%         --       -68%      -100%
date_parse   2774/s       794%       212%         --       -99%
date_calc  374797/s    120730%     42109%     13413%         --