Dimensional (SSAS) Query Performance

[i_am_john]

I have a simple report I have created. It's a couple parameters and a list. This list only has 6 items: two fields from 2 different dimensions and 4 measures.

When I only include either of the dimension fields, the report returns almost immediately. However, when I add one more the time shoots up about 3 minutes.

I can write an MDX query that returns essentially the same list I am looking for and it is immediate. Why is this translated so poorly by Cognos? If I export the MDX Cognos creates, it still takes the same amount of time (~3 min) so it's definitely an issue with MDX the query produces.

Are there any best practices for tuning Cognos queries or setting up an SSAS cube to work better with Cognos?

[CognosPaul]

Do you have any detail filters? How many members in dim 1 and 2?

Can you paste in the generated MDX from the query, when using the gear menu, not from the query itself? Can you paste the MDX that you wrote?