Improve SSAS Tabular query performance

I'be build a Tabular Cube with FactTable and four dimensions. Fact table has about 2.500.000 of rows (and about 20 calculated measures on the cube level) and dimension tables from 5k-50k of rows. When I connect to the cube from Excel and try to add dimension I have to wait like 15-20 seconds for this. Do you know some ways to improve the query performance of such tabular cube (SQL 2014) ? Performance issue not visible (Year consolidated), filtering by Port works fast: Performance issue visible (Year expandeding to weeks takes about 15 sec, filtering by Port after next 15 seconds everytime):