[Plugin: WordPress MU Domain Mapping] Performance: MU-DM Javascript takes lots of time to get genera

A small problem with a script by wordpress-mu-domain-mapping – it slows down my site a lot. It looks like this:

https://sectio-aurea.org/?dm=7b66257d40972188e443498008bdcc5f&action=load&blogid=19&siteid=1&t=1245958239&back=http%3A%2F%2Fblog.ruhrmobil-e.de%2F

To see the problem of slowdown have a look at this site: https://tools.pingdom.com/fpt/ (try https://blog.ruhrmobil-e.de). I get this line at https://blog.ruhrmobil-e.de/, my main site is https://sectio-aurea.org/. Its generated in domain mapping plugin file line 797:
//echo "<script src='{$protocol}{$current_site->domain}{$current_site->path}?dm={$hash}&action=load&blogid={$current_blog->blog_id}&siteid={$current_blog->site_id}&t=" . mt_rand() . "&back=" . urlencode( $protocol . $current_blog->domain . $_SERVER[ 'REQUEST_URI' ] ) . "' type='text/javascript'></script>";

Its part of this function (line 787ff):
function remote_login_js_loader() {

It seems to get generated in this function line 739ff:

function remote_login_js() {
        global $current_blog, $current_user, $wpdb;

        if ( 0 == get_site_option( 'dm_remote_login' ) )
                return false;

        $wpdb->dmtablelogins = $wpdb->base_prefix . 'domain_mapping_logins';
        $hash = get_dm_hash();
        if ( false == isset( $_SERVER[ 'HTTPS' ] ) )
                $_SERVER[ 'HTTPS' ] = 'Off';
        $protocol = ( 'on' == strtolower( $_SERVER[ 'HTTPS' ] ) ) ? 'https://' : 'https://';
        if ( $_GET[ 'dm' ] == $hash ) {
                if ( $_GET[ 'action' ] == 'load' ) {
                        if ( !is_user_logged_in() )
                                exit;
                        $key = md5( time() . mt_rand() );
                        $wpdb->query( $wpdb->prepare( "INSERT INTO {$wpdb->dmtablelogins} ( <code>id</code>, <code>user_id</code>, <code>blog_id</code>, <code>t</code> ) VALUES( %s, %d, %d, NOW() )", $key, $current_user->ID, $_GET[ 'blogid' ] ) );
                        $url = add_query_arg( array( 'action' => 'login', 'dm' => $hash, 'k' => $key, 't' => mt_rand() ), $_GET[ 'back' ] );
                        echo "window.location = '$url'";
                        exit;
                } elseif ( $_GET[ 'action' ] == 'login' ) {
                        if ( $details = $wpdb->get_row( $wpdb->prepare( "SELECT * FROM {$wpdb->dmtablelogins} WHERE id = %s AND blog_id = %d", $_GET[ 'k' ], $wpdb->blogid ) ) ) {
                                if ( $details->blog_id == $wpdb->blogid ) {
                                        $wpdb->query( $wpdb->prepare( "DELETE FROM {$wpdb->dmtablelogins} WHERE id = %s", $_GET[ 'k' ] ) );
                                        $wpdb->query( $wpdb->prepare( "DELETE FROM {$wpdb->dmtablelogins} WHERE t < %d", ( time() - 120 ) ) ); // remote logins survive for only 2 minutes if not used.
                                        wp_set_auth_cookie( $details->user_id );
                                        wp_redirect( remove_query_arg( array( 'dm', 'action', 'k', 't', $protocol . $current_blog->domain . $_SERVER[ 'REQUEST_URI' ] ) ) );
                                        exit;
                                } else {
                                        wp_die( __( "Incorrect or out of date login key", 'wordpress-mu-domain-mapping' ) );
                                }
                        } else {
                                wp_die( __( "Unknown login key", 'wordpress-mu-domain-mapping' ) );
                        }
                } elseif ( $_GET[ 'action' ] == 'logout' ) {
                        if ( $details = $wpdb->get_row( $wpdb->prepare( "SELECT * FROM {$wpdb->dmtablelogins} WHERE id = %d AND blog_id = %d", $_GET[ 'k' ], $_GET[ 'blogid' ] ) ) ) {
                                $wpdb->query( $wpdb->prepare( "DELETE FROM {$wpdb->dmtablelogins} WHERE id = %s", $_GET[ 'k' ] ) );
                                $blog = get_blog_details( $_GET[ 'blogid' ] );
                                wp_clear_auth_cookie();
                                wp_redirect( trailingslashit( $blog->siteurl ) . "wp-login.php?loggedout=true" );
                                exit;
                        } else {
                                wp_die( __( "Unknown logout key", 'wordpress-mu-domain-mapping' ) );
                        }
                }
        }
}

I don’t really have an idea what exacly this function does, especially because its is empty (or perhaps I just don’t get the moment where it’s not empty).

So – can somebody help me out …

• … understanding what exacly this function does
• … understanding why its in top (and not at bottom)
• … make this function much faster?

Thank you!