Performance Issue in Select Statement (For All Entries)

Hello,

I have a report where i have two select statement

First Select Statement:

Select A B C P Q R

     from T1 into Table it_t1

          where ....

Internal Table it_t1 is populated with 359801 entries through this select statement.

Second Select Statement:

Select A B C X Y Z

     from T2 in it_t2 For All Entries in it_t1

          where A eq it_t1-A

             and B eq it_t1-B

             and C eq it_t1-C

Now Table T2 contains more than 10 lac records and at the end of select statement it_t2 is populated with 844003 but it takes a lot of time (15 -20 min) to execute second select statement.

Can this code be optimized?

Also i have created respective indexes on table T1 and T2 for the fields in Where Condition.

Regards,