Large Datasets - How can I improve performance?

Hi

My organisation is using PowerBI on SQL with an Oracle data cube. It is used in multiple businesses and as such there are data fields which contain very large datasets which currently make them unusable in real terms.

I would like to be able to reduce the size of a number of field entries based upon some other selected business criteria.

I am not a programmer or IT expert but a user who is trying to achieve the best I can in reporting capabilities for my Team. In general I have managed to produce some nice, usable reports to improve data visualistion but have this one major challenge.

If I try to apply a Basic Filter to "BT Customer Name" after 5 hours the loaded list is still on the letter C!

What I want to be able to do is along the lines of the following......

I need something that reduces the “BT Customer Name”, “BT Sales Agent Name”, “Sales Rep Name” and “Full Name” fields to only those values applicable when “Product Family Code” = “AUSRV”, “AUTO”, “DATPQ” or “IRCON” as Report Level Filters.

Any ideas/suggestions much appreicated :-) Is it possible in Query Editor or by some other mechanism???

Many Thanks