select ... where ... in(select ..)

[Majdi Swais]

I'm trying to execute the following query
"select f1,f2 from table1 where f2 in (select f3 from table2 where ...)"

The inner select is very simple.
This query takes too much time to execute when table1 contains thousands of rows. If I execute "select f3 from table2 where ...", get the results (let us say 1,5,9,10) and rewrite the query as:
"select f1,f2 from table1 where f2 in (1,5,9,10)", the query will execute very fast (as expected)
Note: both f2 and f3 are integers and indexed, table1 contains 300,000 records

Any ideas
Regards