No, absolutely not. When using a simplified rep in a drawing, only the components active in the simplified rep are brought in to memory. It's just like using a simplified rep in an assembly. The main purpose of a simplified rep is for large assembly management. Some people have gotten creative and used it for product variation more commonly associated to family tables.
I also work on large assemblies and their associated drawings. For a while, we could not open the master rep of our large assemblies mostly due to lack of enough memory. I think that was right after one of the major upgrades, either WF4 to WF5 or WF5 to Creo 2 (not sure which, old man memory is awesome). Our only option until we convinced IT and the boss to upgrade RAM was to aggresively manage our simplified reps.
You if care, you can test this easily by making a simple 2 or 3 part assembly. Make a simplified rep of that assembly by excluding all the components except one. SAVE the assembly. Close the assembly and erase not displayed. Make a new drawing (empty or with format, not with a template), with the assembly as the model and set the rep to the one that only includes the single part. View what has been loaded in to memory using the FILE - MANAGE SESSION - OBJECT LIST. It should only show the drawing, the assembly and the one part, not the other part(s) excluded using the simplified rep.