Оптимизация вложенного SQL запроса

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Теперь к вопросу: имеется sql запрос

SELECT `tema`.*, 
   (SELECT Count(*) 
    FROM   `post` 
    WHERE  `post`.`id_tema` = `tema`.`id`) AS `count_post`, 
   (SELECT `id` 
    FROM   `post` 
    WHERE  `post`.`id_tema` = `tema`.`id` 
    ORDER  BY `id` DESC 
    LIMIT  1)  AS `id_post`, 
   (SELECT `login` 
    FROM   `users` 
    WHERE  `users`.`id` = (SELECT `id_user` 
                           FROM   `post` 
                           WHERE  `post`.`id_tema` = `tema`.`id` 
                           ORDER  BY `id` DESC 
                           LIMIT  1)
   )  AS `login` 
FROM   `tema` 
WHERE  `id_forum` = '4' 
ORDER  BY `up` DESC, `time` DESC 
LIMIT  3260, 20 

Срок выполнения - 2.7 секунды.

Структура БД:

--
-- Структура таблицы `tema`
--
DROP TABLE IF EXISTS `tema`;
CREATE TABLE IF NOT EXISTS `tema` (
`id` int(11) NOT NULL auto_increment,
`id_razdel` int(11) NOT NULL,
`id_forum` int(11) NOT NULL,
`id_user` int(11) NOT NULL,
`name` varchar(500) NOT NULL,
`translate` varchar(500) NOT NULL,
`text` text NOT NULL,
`time` int(11) NOT NULL,
`up` enum('0', '1') NOT NULL default '0',
`closed` enum('0', '1') NOT NULL default '0',
`count` int(11) NOT NULL default '0',
PRIMARY KEY (`id`),
KEY `id_razdel` (`id_razdel`),
KEY `id_forum` (`id_forum`),
KEY `id_user` (`id_user`),
KEY `time` (`time`),
KEY `up` (`up`),
FULLTEXT KEY `name` (`name`)
) ENGINE=MyISAM DEFAULT CHARSET=utf8;
--
-- Структура таблицы `post`
--
DROP TABLE IF EXISTS `post`;
CREATE TABLE IF NOT EXISTS `post` (
`id` int(11) NOT NULL auto_increment,
`id_razdel` int(11) NOT NULL,
`id_forum` int(11) NOT NULL,
`id_tema` int(11) NOT NULL,
`id_user` int(11) NOT NULL,
`text` text NOT NULL,
`cit` int(11) NOT NULL,
`time` int(11) NOT NULL,
`timeedit` int(11) NOT NULL,
`kedit` int(11) NOT NULL,
`id_user_edit` int(11) NOT NULL,
`vote` varchar(11) NOT NULL,
PRIMARY KEY (`id`),
KEY `id_razdel` (`id_razdel`),
KEY `id_forum` (`id_forum`),
KEY `id_tema` (`id_tema`),
KEY `id_user` (`id_user`),
KEY `time` (`time`),
FULLTEXT KEY `text` (`text`)
) ENGINE=MyISAM DEFAULT CHARSET=utf8;

Explain запроса

Собственно вопрос: как можно оптимизировать данный sql запрос?