$d1 = '14', $m1 = '08', $y1 = '2001';
$d2 = '16', $m2 = '12', $y2 = '2001';
$dt1 = "2001/08/14";
$dt2 = "2001/12/16";

timethese(-10, {  # running for at least 10 seconds
			'Calc' => \&Calc,
			'Manip' => \&Manip,
		});

sub Calc {
	my $Dd = Date::Calc::Delta_Days($y1,$m1,$d1,$y2,$m2,$d2);
}

sub Manip {
	my $date1=Date::Manip::ParseDate($dt1);
	my $date2=Date::Manip::ParseDate($dt2);
	my $flag=Date::Manip::Date_Cmp($date1,$date2);
}

##</code><code>##

Benchmark: running Calc, Manip, each for at least 10 CPU seconds...
Calc: 12 wallclock secs (11.04 usr +  0.00 sys = 11.04 CPU) 
      @ 142935.85/s (n=1577440)
Manip:10 wallclock secs (10.56 usr +  0.00 sys = 10.56 CPU) 
      @ 104.88/s (n=1107)