sql - 複数のサブクエリを最小限に抑える方法は?

Question

where句にネストされたクエリがいくつかあることがわかるように、次のクエリは少し遅いですが、より良い解決策を思い付くことができますか?

SELECT m.briefmedialist, 
       Count(DISTINCT s.value) AS selected, 
       m.briefmedialistid 
FROM   vwmedialistmediachannels m 
       LEFT JOIN sessionfilters s 
              ON s.field = 'Media' 
                 AND m.briefmedialistid = s.value 
                 AND s.sessionid = @SessionID 
WHERE  m.id = (SELECT d.briefid 
               FROM   dashboards d 
               WHERE  d.dashboardguid IN (SELECT value 
                                          FROM   sessionfilters s 
                                          WHERE  s.sessionid = @SessionID 
                                                 AND s.field = 'DashboardID')) 
GROUP  BY m.briefmedialist, 
          m.briefmedialistid 
ORDER  BY m.briefmedialist