SSAS: optimizing processing query using reference dimension relationship

In one of my former posts titled "Select Facts with Reference and Many2Many relationships" i blogged about the usage of reference dimension relationships in cubes. In my current clientsituation i'm experiencing a major slowdown processing the cube. Some investigation learned that the reference relationsshiop seems to be the problem. In this blogpost i'll explain the problem, slowdown processing the cube, a solution, by replacing the load query and a conclusion.