find.php

<?php
        $posts = $this->Post->find('all', array(
            'contain' => array(
                'Comment' => array(
                    'Commenter'
                ),
            )
        ));

sql.log

1	SELECT `Post`.`id`, `Post`.`user_id`, `Post`.`title`, `Post`.`body`, `Post`.`published`, `Post`.`allow_comments`, `Post`.`created` FROM `test_database_name`.`posts` AS `Post` WHERE 1 = 1		5	5	0
2	SELECT `Comment`.`id`, `Comment`.`post_id`, `Comment`.`user_id`, `Comment`.`comment`, `Comment`.`created` FROM `test_database_name`.`comments` AS `Comment` WHERE `Comment`.`post_id` IN (1, 2, 3, 4, 5)		3	3	1
3	SELECT `Commenter`.`id`, `Commenter`.`name`, `Commenter`.`bio`, `Commenter`.`created` FROM `test_database_name`.`users` AS `Commenter` WHERE `Commenter`.`id` = 1		1	1	0
4	SELECT `Commenter`.`id`, `Commenter`.`name`, `Commenter`.`bio`, `Commenter`.`created` FROM `test_database_name`.`users` AS `Commenter` WHERE `Commenter`.`id` = 2		1	1	0
5	SELECT `Commenter`.`id`, `Commenter`.`name`, `Commenter`.`bio`, `Commenter`.`created` FROM `test_database_name`.`users` AS `Commenter` WHERE `Commenter`.`id` = 1		1	1	0

5 posts, and 3 comments = 5 queries
100 posts and 3 comments = 5 queries
5 posts and 100 comments = 102 queries.