Wolfgang Strasser points out a new feature in Power BI Desktop:
In some cases, sources for Direct Query models are either large (and therefore need some time to bring back the data) or slow (which could maybe be improved by some database tuning :-)).
Before the Nov2017 release, every change in a filter or slicer led to an immediate round trip to the data source which made some of those reports … let’s call it .. not perfect in the context of user experience.
Beginning with the Nov2017 release some options for Query Reduction has been introduced.
Click through for an example of how to use Query Reduction on direct query models.