The optimization process and recommendations:

1. Avoid Selecting Unnecessary Columns (query line: 14): Avoid selecting all columns with the '*' wildcard, unless you intend to use them all. Selecting redundant columns may result in unnecessary performance degradation.
2. Create Optimal Indexes (modified query below): The recommended indexes are an integral part of this optimization effort and should be created before testing the execution duration of the optimized query.
3. Explicitly ORDER BY After GROUP BY (modified query below): By default, the database sorts all 'GROUP BY col1, col2, ...' queries as if you specified 'ORDER BY col1, col2, ...' in the query as well. If a query includes a GROUP BY clause but you want to avoid the overhead of sorting the result, you can suppress sorting by specifying 'ORDER BY NULL'.
4. Use Numeric Column Types For Numeric Values (query line: 30): Referencing a numeric value (e.g. 1) as a string in a WHERE clause might result in poor performance. Possible impacts of storing numbers as varchars: more space will be used, you won't be able to perform arithmetic operations, the data won't be self-validated, aggregation functions like SUM won't work, the output may sort incorrectly and more. If the column is numeric, remove the quotes from the constant value, to make sure a numeric comparison is done.

Optimal indexes for this query:

ALTER TABLE `shoop_posts` ADD INDEX `shoop_posts_idx_thread_id` (`thread_id`);
ALTER TABLE `shoop_tags` ADD INDEX `shoop_tags_idx_tag_id` (`tag_id`);
ALTER TABLE `shoop_tags_map` ADD INDEX `shoop_map_idx_thread_id` (`thread_id`);
ALTER TABLE `shoop_users` ADD INDEX `shoop_users_idx_user_id` (`user_id`);

The optimized query:

SELECT
        GROUP_CONCAT(t.tag_name) AS `tags`,
        `p`.`thread_id`,
        `p`.`thread_name`,
        `p`.`thread_description`,
        `p`.`thread_owner_id`,
        `p`.`thread_view_count`,
        `p`.`thread_reply_count`,
        `p`.`thread_comment_count`,
        `p`.`thread_favorite_count`,
        `p`.`thread_creation_date`,
        `p`.`thread_type_id`,
        `p`.`thread_edited_date`,
        `u`.*,
        `x`.*,
        `t`.* 
    FROM
        `shoop_posts` AS `p` 
    INNER JOIN
        `shoop_users` AS `u` 
            ON u.user_id = p.thread_owner_id 
    LEFT JOIN
        `shoop_tags_map` AS `x` 
            ON x.thread_id = p.thread_id 
    LEFT JOIN
        `shoop_tags` AS `t` 
            ON t.tag_id = x.tag_id 
    WHERE
        (
            p.thread_id = '1'
        ) 
    GROUP BY
        `p`.`thread_id` 
    ORDER BY
        NULL