Does anyone know that maximum number of sub-projects that can be created under a master project on server before the performance starts to diminish? I know the number of tasks can diminish performance, but I am not sure about sub-projects.
Meghan, to be honest for the master project, performance will start to diminish with one. Opening the master project will open all subprojects with a certain amount of overhead. Answering the core of your question is a bit impossible without understanding your network, PC, Project Server vs. Online, number of tasks, resources, assignments, etc.