This section contains several system related settings. All changes to these settings are global, ie. it might affect current sessions. Check how many users are signed in to the system before changing any of these settings. Check out the statistics to get an overview of how busy the system is currently. In particular, pay attention to the following:

Form sessions
The number of currently active form sessions. That is, the number of who have a form opened in their browsers.
Application sessions
The number of users currently signed in to the backend. Your own session is not counted.