sql - SQL クエリのパフォーマンス (相関サブクエリ) を改善するにはどうすればよいですか?

Question

以下のクエリをより効率的で効率的な方法で書きたいと思いますか?

SELECT   a.assetnum as Asset,
         a.assettag as Asset_Tag,
         a.manufacturer as Manufacturer,
         a.serialnum as Serial,
         a.description as Description,
         (
             SELECT CASE  a.isrunning
                    WHEN  1 
                    THEN  'Operational' 
                    WHEN  0 
                    THEN  'Down' 
                    END
         ) AS  Condition ,
         l.kbs_loctag as Location,
         (
             SELECT TOP 1 wo.wonum 
             FROM   workorder wo 
             WHERE  wo.assetnum = a.assetnum
                    and wo.worktype = 'UN'
             ORDER BY wo.reportdate DESC
         ) AS Last_Workorder,
         (
             SELECT wo.statusdate 
             FROM   workorder wo 
             WHERE  wo.wonum IN
                    (
                        SELECT   top 1 wo.wonum 
                        FROM     workorder wo
                        WHERE    wo.assetnum = a.assetnum
                                 AND wo.worktype = 'UN'
                        ORDER BY wo.reportdate DESC
                    )
         ) AS Last_Status_Date,
         (
             SELECT top 1 lt.memo
             FROM   labtrans lt
             WHERE  lt.assetnum = a.assetnum 
                    AND lt.transtype = 'REPAIR'
             ORDER BY lt.transdate DESC
       ) AS Action
FROM   asset a 
       LEFT OUTER JOIN locations l
           ON a.location = l.location
WHERE  (
           a.description like '%WASH%' 
           or a.description LIKE '%DRYER%'
       )
ORDER BY  l.location, 
       a.description