Perfomance issue-Taking more time to load

[cognos05]

Hi,
I am using a dimensional package
Level 5 and level 4 as cascading prompt from same dimension.

Scenario 1 :
ROws- Level 4, level3, Level 2 Nested

Scenario 2:

Instead of nesting rows ,i stacked them using Union operator for all 5 levels and used Hierarchize function and indented.


Now when i change the value prompt value for my level 4 , my scenario 2  takes more time to load, but scenario 1 works faster.

Is this trying to go back to my tm1 data base every time I change my level 4 value for scenario 2 - does union () goes to tm1 and recalculates the values wheres rows nested in case1 just filters from existing data ?

What could be the reason.

Any help is appreciated.

Thanks,
Nithya