In Power BI desktop, we need to apply the required query change to load to data model. In your scenario, please go to File-> Options -> Data load, check if you have enable the option "Parallel loading of tables". Enable this feature will reduce time when loading multiple tables.
Also please try to run the latest desktop version: 2.50.4859.502 64-bit (September 2017).
Best Regards, Qiuyun Yu
Community Support Team _ Qiuyun Yu If this post helps, then please consider Accept it as the solution to help the other members find it more quickly.