Query demorando muito para retorno.

Estouterndo problema com a query abaixo...

Ela está demorando entre 6,5 a 7 segundos para retornar resposta.

Tem algo errado nela ?

SELECT
 `post`.`id_post`,
 `post`.`id_user`,
 `post`.`default_name`,
 `post`.`description`,
 `post`.`visibility`,
 `post`.`gmdate_ref`,
 `post`.`comment_count`,
 `post`.`approved_count`,
 `post`.`disapproved_count`,
 `post`.`location`,
 `post`.`timezone_offset`,
 `post`.`timezone_name`,
 `post`.`timestamp`,
 `user_profile`.`first_name`,
 `user_profile`.`last_name`,
 `user_profile`.`display_name`,
 `user_profile`.`photo`,
 `user_profile`.`url_profile`
 FROM
 `post`
 INNER JOIN `user_profile` ON `user_profile`.`id_user` = `post`.`id_user`
 LEFT JOIN `users_linked` ON `post`.`id_user` = `users_linked`.`id_user_linked`
 WHERE
 (`users_linked`.`id_user` = 2
 AND
 `users_linked`.`on_feed` = 1
 AND
 `users_linked`.`link_status` = 2
 AND
 `post`.`visibility` IN (1,0)

 AND timestamp <= FROM_UNIXTIME(1400261402))
 OR
 (`users_linked`.`id_user` = 2
 AND
 `users_linked`.`on_feed` = 1
 AND
 `users_linked`.`link_status` = 0
 AND
 `post`.`visibility`=0

 AND timestamp <= FROM_UNIXTIME(1400261402))
 OR
 (`post`.`id_user` = 2

 AND timestamp <= FROM_UNIXTIME(1400261402))
 GROUP BY
 `post`.`id_post`
 ORDER BY
 `timestamp` DESC LIMIT 0,20