It depends on your definition of "slow". I can create 10000 timestamps in ~3 seconds (Increased from 1000 to 10000 for more reliable count) with DateTime, which is also considered "slow" by some.

use strict;
use warnings;
use DateTime;
use Benchmark qw(timethis);

my $dt = DateTime->new(
  year   => 2011,
  month  => 1,
  day    => 1,
  hour   => 0,
  minute => 0,
  second => 0,
);

timethis(
  10000,
  sub {
    print $dt->ymd() . ' ' . $dt->hms;
    $dt->add(hours => 1, minutes => 2, seconds => 3);
  }
);

timethis(
  10000,
  sub {
    $dt->add(hours => 1, minutes => 2, seconds => 3);
  }
);

__END__
# Calc + print
timethis 10000:  3 wallclock secs ( 3.09 usr +  0.06 sys =  3.15 CPU) 
+@ 3174.60/s (n=10000)
# Just calc:
timethis 10000:  3 wallclock secs ( 2.95 usr +  0.00 sys =  2.95 CPU) 
+@ 3389.83/s (n=10000)
[download]

If you are really in a hurry, the general consensus is to use Date::Calc. However, with it you would have to do more of the sprintf() formatting yourself.

use strict;
use warnings;
use DateTime;
use Date::Calc qw (Add_Delta_DHMS);
use Benchmark qw(cmpthese);

my $dt = DateTime->new(
  year   => 2011,
  month  => 1,
  day    => 1,
  hour   => 0,
  minute => 0,
  second => 0,
);

my ($year, $month, $day, $hour, $min, $sec) = (2011, 1, 1, 0, 0, 0);

cmpthese(
  -1,
  {
    'DateTime' => sub {
      print $dt->ymd() . ' ' . $dt->hms;
      $dt->add(hours => 1, minutes => 2, seconds => 3);
    },
    'Date::Calc' => sub {
      print $year . '-' . $month . '-' . $day . ' ' . $hour . '-' . $m
+in . '-'
        . $sec;
      ($year, $month, $day, $hour, $min, $sec) =
        Add_Delta_DHMS($year, $month, $day, $hour, $min, $sec, 0, 1, 2
+, 3);
    },
  }
);


__END__

$ perl -l 883070.pl | tail -5
2011-07-18 10:20:15
2011-07-18 11:22:18
               Rate   DateTime Date::Calc
DateTime     3258/s         --       -99%
Date::Calc 481882/s     14690%         --
$
[download]

Updated Wed Jan 19 11:12:58 CET 2011 with Date::Calc example.

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