Combine
This group contains Boolean tools and other means of joining geometry together.
Faster and Better Drills and Booleans
Complex Drill and Boolean operations require a lot of computing. Selecting the affected polygons in the foreground layer before using either command will greatly speed things up. This lets Modeler concentrate on only those polygons that need to be affected. Also, if your initial result is not satisfactory - particularly with complex objects - try it again after nudging one of the objects on an axis a little.