use Date::Format;
use DateTime;
use Benchmark qw(cmpthese);

sub lt {
    my @lt = localtime;
    return sprintf(
        "%d-%02d-%02d %02d:%02d:%02d",
        $lt[5] + 1900, $lt[4] + 1, $lt[3],
        $lt[2],        $lt[1],     $lt[0]
    );
}

sub df {
    @lt = localtime;
    return Date::Format::strftime( "%Y-%m-%d %T", @lt );
}

sub dt1 {
    return DateTime->now( time_zone => "local" )->strftime("%F %T");
}

my $tz = DateTime::TimeZone->new( name => 'local' );
sub dt2 {
    return DateTime->now( time_zone => $tz )->strftime("%F %T");
}

cmpthese(
    100000,
    {
        localtime              => \&lt,
        'Date::Format'         => \&df,
        'DateTime'             => \&dt1,
        'DateTime (cached tz)' => \&dt2,
    }
);