I am using DateTime in a while loop with over 1 million (up to 300 million) lines to calculate a date & time field. Currently I had all of the code in the while loop. I moved the $formatter code outside of the while loop. But the speed is very slow. The primary reason I am using the DateTime module is to convert the data which is in UTC to New York time. The date changes since I am going past 12AM with the time zone change. Any suggestions on how I can speed this up? Should I avoid DateTime due to the number of rows? 
while(<>){

chomp;
$line = $_;
my @line = split(';',$line);

$line[4] =~ s/:/\//;
($month) = $line[4] =~ m/(\d+)\/\d+/;
($day) = $line[4] =~ m/\d+\/(\d+)/;

$hour = (int($line[7]/3600000)) % 24;
$minute = sprintf '%02d', (int($line[7]/60000)) % 60;
$second = sprintf '%02d', (int($line[7]/1000)) % 60;
$ms = sprintf '%03d', $line[7] % 1000;

$formatter = new DateTime::Format::Strptime(
    pattern => '%Y-%m-%d %H:%M:%S.%3N');

$dhms = DateTime->new(year => $line[5],
                          month => $month,
                          day => $day,
                          hour => $hour,
                          minute => $minute,
                          second => $second,
                          nanosecond => $ms * 1000000,
                          time_zone => 'Etc/UTC',
                          formatter => $formatter,
                          );

$dhms = $dhms->clone->set_time_zone('America/New_York');
}

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In reply to DateTime speed improvement - suggestion by ler224

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