This step-by-step article demonstrates how to disable session state in ASP.NET.
When session state is enabled, ASP.NET creates a session for every user who accesses the application, which is used to identify the user across pages within the application. When session state is disabled, user data is not tracked, and you cannot store information in the Session object or use the Session_OnStart or Session_OnEnd events. By disabling session state, you can increase performance if the application or the page does not require session state to enable it.
In ASP.NET, if you do not use the Session object to store any data or if any of the Session events (Session_OnStart or Session_OnEnd) is handled, session state is disabled. A new Session.SessionID is created every time a single page is refreshed in one browser session.