When should I use Reference Type nodes?

Let's say I have N-numbers of levels. Each level contains nodes of the same type. If I create nodes in separate .scn files and add them to the scenes as Reference Type nodes, how will this affect on performance? Positive or negative? My guess is that this approach will have a positive affect on performance, because once a node is loaded, the app will need less time to load the node when the same node appears on scene, as we have loaded a node of this type (design) before. Isn't that right? Or not? Although, maybe, Reference Type nodes are only helpful because I do not have to repeat the same work each time.