I was doing a test on my multisite by logging in 15 of my user sites (on my machine from one IP Address) in preparation for a live class I'm planning with 15 students.
I wanted to see how much CPU usage there might be when all 15 students are working inside their dashboard simultaneously. I want to be sure my shared server can handle it.
The server seemed to be fine, but I did notice that many of the sites were periodically logged out by the system. I don't know if this was because they are all logged in on my machine, or because I have less-than-great Internet connection, or if there was something that WordPress didn't like about so many sites working in the dashboard at once. I tried to simulate what we're going to be doing in class: adding and editing pages, changing settings, working with the theme options, adding and editing widgets...all the usual stuff.
Does anyone have any ideas as to why the user sites would be getting logged out so frequently? And is so, is there anything to do to mitigate this problem?