There are several ways to improve the performance of the simulation by simply simplifying or optimizing the geometries.
Inside 3DCreate, there are two very useful tools that achieve this. When you have the Geometry Set filter on, select the geo set you want to optimize, and right click on it in the 3Dworld. The context-sensitive menu should give you the "Optimize all Geosets" options. For large geometries, this can take up to ten minutes, so be patient.
Another way of optimizing the geometry, it to merge all boundar points. This is done on the Feature selection filter. Right click on the geometry feature, and select "Merge Feature Boundary Points". This should be quite fast, but optimizes the geometry considerably.