Improve speed of MySQL query with 5 left joins

Working on a support ticketing system with not a lot of tickets (~3,000). To get a summary grid of ticket information, there are five LEFT JOIN statements on custom field table (j25_field_value) containing about 10,000 records. The query runs too long (~10 seconds) and in cases with a WHERE clause, it runs even longer (up to ~30 seconds or more).

Any suggestions for improving the query to reduce the time to run?

Four tables:

• j25_support_tickets

  CREATE TABLE `j25_support_tickets` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `category_id` int(11) NOT NULL DEFAULT '0',
  `user_id` int(11) DEFAULT NULL,
  `email` varchar(50) DEFAULT NULL,
  `subject` varchar(255) DEFAULT NULL,
  `message` text,
  `modified_date` datetime DEFAULT NULL,
  `priority_id` tinyint(3) unsigned DEFAULT NULL,
  `status_id` tinyint(3) unsigned DEFAULT NULL,
  PRIMARY KEY (`id`),
  UNIQUE KEY `id` (`id`)
  ) ENGINE=MyISAM AUTO_INCREMENT=3868 DEFAULT CHARSET=utf8
  

• j25_support_priorities

  CREATE TABLE `j25_support_priorities` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `title` varchar(100) DEFAULT NULL,
  PRIMARY KEY (`id`),
  UNIQUE KEY `id` (`id`)
  ) ENGINE=MyISAM AUTO_INCREMENT=14 DEFAULT CHARSET=utf8
  

• j25_support_statuses

  CREATE TABLE `j25_support_statuses` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `title` varchar(255) DEFAULT NULL,
  PRIMARY KEY (`id`),
  UNIQUE KEY `id` (`id`)
  ) ENGINE=MyISAM AUTO_INCREMENT=7 DEFAULT CHARSET=utf8
  

• j25_field_value (id, ticket_id, field_id, field_value)

  CREATE TABLE `j25_support_field_value` (
  `id` int(10) unsigned NOT NULL AUTO_INCREMENT,
  `ticket_id` int(11) DEFAULT NULL,
  `field_id` int(11) DEFAULT NULL,
  `field_value` tinytext,
  PRIMARY KEY (`id`)
  ) ENGINE=MyISAM AUTO_INCREMENT=10889 DEFAULT CHARSET=utf8
  

Also, ran this:

    SELECT LENGTH(field_value) len FROM j25_support_field_value ORDER BY len DESC LIMIT 1
    note:  the result = 38

The query:

SELECT DISTINCT t.id as ID
, (select p.title from j25_support_priorities p where p.id = t.priority_id) as Priority
, (select s.title from j25_support_statuses   s where s.id = t.status_id)   as Status
,     t.subject       as Subject
,     t.email         as SubmittedByEmail
,  type.field_value   AS IssueType
,   ver.field_value   AS Version
, utype.field_value   AS UserType
,  cust.field_value   AS Company
, refno.field_value   AS RefNo
, t.modified_date     as Modified
    FROM j25_support_tickets AS t
LEFT JOIN j25_support_field_value AS type  ON t.id = type.ticket_id  AND  type.field_id =1
LEFT JOIN j25_support_field_value AS ver   ON t.id = ver.ticket_id   AND   ver.field_id =2
LEFT JOIN j25_support_field_value AS utype ON t.id = utype.ticket_id AND utype.field_id =3
LEFT JOIN j25_support_field_value AS cust  ON t.id = cust.ticket_id  AND  cust.field_id =4
LEFT JOIN j25_support_field_value AS refno ON t.id = refno.ticket_id AND refno.field_id =5