Hi Gary, Having many accounts open can use up RAM, and yes, any background tasks in one desktop should continue running when you swap to another desktop (which is a potential cause of slowdowns). It is also possible to set up access to all desktops simultaneously, or even to share desktops remotely over a network.
In my experience, Fast User Switching is manageable especially if people quit unused apps when switching to another user. If you are having difficulties, you can use the Activity Monitor to identify what processes are using the most CPU or RAM. The Activity Monitor is inside the Utilities folder inside the Applications folder. James.
