Just the capability to share memory with other apps is what requires the sacrifice in efficiency. It means that apps can't control what and when parts of themse

Just the capability to share memory with other apps is what requires the sacrifice in efficiency. It means that apps can't control what and when parts of themselves are paged out to disk. If they could, they might only page out infrequently used data, as opposed to data that needs to be available quickly for responsiveness.