一个怪异的现象，语句特别慢，帮分析原因

  SELECT    *

  FROM      CSKH  ccc

            INNER JOIN ( SELECT a.fgsid , 

                                SUM(a.je) AS je ,

                                COUNT(*) AS kll ,

                                SUM(bs) AS bs ,

                                SUM(sl) AS sl ,

                                SUM(ml) AS ml

                         FROM   ( SELECT    fgsid ,

                                            lsh ,

                                            SUM(je) AS je ,

                                            SUM(sl) AS sl ,

                                            COUNT(*) AS bs ,

                                            SUM(ml) AS ml

                                  FROM      fgs_xsd (NOLOCK)

                                 WHERE     kdrq BETWEEN '2012-12-01'

                                                 AND     DATEADD(day, 1, '2012-12-11')

                                  GROUP BY  fgsid ,

                                            lsh

                                ) a

                         GROUP BY a.fgsid

                       ) b 

                       ON ccc.id = b.fgsid