how-to implement memory efficient asp.net C# application

SOURCES:
http://aspalliance.com/520_Detecting_ASPNET_Session_Timeouts.2
Base Page and User Control Classes

using System;
using System.Collections;
using System.Configuration;
using System.Data;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.HtmlControls;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;

public class CustomBasePage : System.Web.UI.Page
{
  public CustomBasePage ()
  {
  }

  override protected void OnInit ( EventArgs e )
  {
   ClearAllNonGlobalSessionsButMine ();
}
  private void ClearAllNonGlobalSessionsButMine( )
  {
    string fileNameNoExt = System.IO.Path.GetFileNameWithoutExtension (
                System.Web.HttpContext.Current.Request.Url.AbsolutePath );

    for (int i = 0 ; i< HttpContext.Current.Session.Count ;i ++ ) 
    {
      string keyValue = HttpContext.Current.Session.Keys [ i ];
      if (keyValue.Contains ( fileNameNoExt ) || keyValue.Contains ( "global" ))
      { ; }    //do nothing = preserve the value in the session 
      else
      {
        Utils.Debugger.WriteIf ( "Deleting ---- " + HttpContext.Current.Session [ HttpContext.Current.Session.Keys [ i ] ] );
        HttpContext.Current.Session [ HttpContext.Current.Session.Keys [ i ] ] = null;
      } //eof else if it is global or belongs to current page
        

    } //eof loop 
    
  } //eof public static void ClearAllButCurrent (string pageName )  

} //eof BasePageClass