Tips for Creating a Map Document
The following guidelines about creating map documents and the features to include will improve performance.
When a network feature class is included in a map, all feature classes from the network (including default junctions) should be included as well. They don't all have to be visible, they just need to be included in the map.
If a feature class is included in a map, all related feature and object classes should be included as well (including empty classes).