Table and grouping.

Hello BIRT community,

I habe a problem with Table and grouping.

I have made my export to PRF with 3 tables. The first in the main table and then I have inner and inner/inner table. All are bound with grouping rules. My problem is that when many item should be displayed then it takes too much time. by 200 items 40 seconds. I think it calucates the tabels like loops so at the end I have something like n^3.

I am trying now to do that with one table. How can I display groups on one level. I need something like this:

--------------------------
Title(Group1)
--------------------------
Nr(Group2)   text(Group3) value   time
                          value
             text         value   
                          value

where Nr and time are on the top level, then text in on the second and value is on the third level.

For any hint, suggestion or examples thanks in advance.