请问,如何修改下面的sql语句,从而提高性能,具体sql如下

Question

--本期应开票金额---耗时350/60 5.9分钟

SELECT T1.FAsstActID,
  SUM(T2.FRecievePayAmountLocal) AS BQYSAMOUNT
FROM T_AR_OtherBill T1
INNER JOIN T_AR_OtherBillentry  T2 ON T1.FID=T2.FParentID 
where  (to_char(T1.FBizDate,'YYYY-MM-DD') >= '2016-02-01' 
AND to_char(T1.FBizDate,'YYYY-MM-DD') <= '2019-04-03'  )
AND ( T1.FCurrencyID = '' OR null IS NULL  )
AND ( T1.FBillStatus =3 )
AND  ( T1.FCompanyID =  'sREAAAAAB9LM567U')
GROUP BY T1.FAsstActID 

下面一段是我根据上面一段优化后的sql,但是感觉不行,请问没有没有更好的优化?
--优化后

SELECT T1.FAsstActID,
SUM(T2.FRecievePayAmountLocal) AS BQYSAMOUNT
FROM (SELECT FAsstActID,FID 
     FROM  T_AR_OtherBill 
     WHERE (to_char(FBizDate,'YYYY-MM-DD') >= '2016-02-01' 
     AND to_char(FBizDate,'YYYY-MM-DD') <= '2019-04-03'  )
     AND ( FCurrencyID = '' OR null IS NULL  )
     AND ( FBillStatus =3 )
     AND  ( FCompanyID =  'sREAAAAAB9LM567U'  )
) T1 
INNER JOIN T_AR_OtherBillentry T2 ON T1.FID=T2.FParentID 
GROUP BY T1.FAsstActID