Tibco SPOTFIRE 7.5 Data Connector witn Custom query and fields prompted

Someone have used Data Connector with Custom queries and definition of Prompt?

I have a data connector with a custom query on a Oracle DB view with around 30 mln of record.

We have defined a set of PROMPTS on the data connection for around 5 fields, to filter rows when we use Analyst. 

The issue is that when we open the data connector, Analyst spent much more time to pass from a prompt to another even if the query underlying spent very few seconds to retrive the list of value to visualize in the single selection prompt. 

Someone can help me?