"Using Temporary" with a Custom Wordpress Search

I currently use a custom wordpress MySQL query to get related products for some of my shopping sites. I've just profiled my pages and i've noticed that this query takes about 3 seconds, yet i'm unsure how to optimise it. The query is below:

explain select 
    p . *,
    unix_timestamp(p.post_modified) as post_modified_ut,
    unix_timestamp(p.post_date) as post_date_ut,
    (((2.3 * (MATCH (p.post_title) AGAINST ('Motorola+MBP+36+Digital+Video+Monitor' IN BOOLEAN MODE)))) + (0.6 * (MATCH (p.post_content) AGAINST ('Motorola+MBP+36+Digital+Video+Monitor' IN BOOLEAN MODE)))) AS relevance
from
    wp_posts as p,
    wp_terms as t,
    wp_term_taxonomy as tt,
    wp_term_relationships as tr
where
    (MATCH (p.post_title , p.post_content) AGAINST ('Motorola+MBP+36+Digital+Video+Monitor' IN BOOLEAN MODE))
        and tr.object_id = p.ID
        and tr.term_taxonomy_id = tt.term_taxonomy_id
        and tt.term_id = t.term_id
        and p.post_type = 'post'
        and p.post_status in ('inherit' , 'publish')        
group by p.ID , p.post_title
order by relevance desc
limit 5;

The result from the explain is:

+----+-------------+-------+--------+-------------------------------------------------+------------------+---------+------------------------------------+------+---------------------------------+
| id | select_type | table | type   | possible_keys                                   | key              | key_len | ref                                | rows | Extra                           |
+----+-------------+-------+--------+-------------------------------------------------+------------------+---------+------------------------------------+------+---------------------------------+
|  1 | SIMPLE      | tt    | ALL    | PRIMARY,term_id_taxonomy                        | NULL             | NULL    | NULL                               | 2822 | Using temporary; Using filesort |
|  1 | SIMPLE      | t     | eq_ref | PRIMARY                                         | PRIMARY          | 8       | reviewexplorer.tt.term_id          |    1 | Using index                     |
|  1 | SIMPLE      | tr    | ref    | PRIMARY,term_taxonomy_id                        | term_taxonomy_id | 8       | reviewexplorer.tt.term_taxonomy_id |    5 |                                 |
|  1 | SIMPLE      | p     | eq_ref | PRIMARY,type_status_date,searches,searches_more | PRIMARY          | 8       | reviewexplorer.tr.object_id        |    1 | Using where                     |
+----+-------------+-------+--------+-------------------------------------------------+------------------+---------+------------------------------------+------+---------------------------------+

As you can see i'm using temporary tables and i dont want to, I'd like to create an index to speed up this query but i dont fully understand what the explain is telling me.