获取两个日期列之间的时间差

Question

我有这个查询来获取活动之间的时间差距，其中只显示间隔小于10小时的活动。 它运行非常非常慢。大约有300项活动，差距不到10小时。对性能的任何建议？

WITH GapsBetweenActivities AS
(
    SELECT  ACTIVITY_ID
            ,ACTIVITY_START_TIME            
            ,DATEDIFF(MINUTE, ACTIVITY_START_TIME, LAG(ACTIVITY_START_TIME) OVER (ORDER BY ACTIVITY_START_TIME)) AS PREVIOUS_ACTIVITY         
    FROM    ACTIVITIES  
    WHERE   ACTIVITY_START_TIME > GETDATE() -- FUTURE ACTIVITY
)

SELECT  *
FROM    GapsBetweenActivities
WHERE   PREVIOUS_ACTIVITY IS NULL -- NULL PREVIOUS ACTIVITY (FIRST ONE IN TABLE)
        OR
        PREVIOUS_ACTIVITY > -600; -- DATE DIFF IS NEGATIVE MINUTES