Why Tank_Auth so slowly?

[eluser]vps4[/eluser]
I just installed it.
and run the login page.

Page rendered in 1.1861 seconds, 3 queries, 0.43MB memory usage.

it seems not database problem. but why it so slowly?

[queries] => Array
(
[0] => SELECT *
FROM (`ci_sessions`)
WHERE `session_id` = 'bbd465e211d0634d9ebf076fd75ced52'
AND `user_agent` = 'Opera/9.63 (Windows NT 5.1; U; Edition IBIS; zh-cn'
[1] => SELECT 1
FROM (login_attempts)
WHERE `ip_address` = '127.0.0.1'
[2] => SELECT 1
FROM (login_attempts)
WHERE `ip_address` = '127.0.0.1'
)

[query_times] => Array
(
[0] => 0.000450134277344
[1] => 0.000540018081665
[2] => 0.000316143035889
)

and in the controller file
/* Location: ./application/controllers/auth.php */
I add benchmark for login function
it just take 0.08 second.

so, where it expend time?

EDIT:
I add benchmark for the __construct function

$this->benchmark->mark('startc');
$this->load->config('tank_auth', TRUE);
$this->load->helper(array('form', 'url'));
$this->load->library('form_validation');
$this->load->library('tank_auth');
$this->lang->load('tank_auth');
$this->benchmark->mark('endc');

it take 0.70 second.

How can I optimize it? and where is the other time?