Some other process may be eating up your resources. I had this with the latest Nvidia drivers making me lag in full screen, after I disabled the helper processes of Nvidia my lag was gone. This is a nice utility which shows, among other stuff, the CPU usage per running process: http://www.microsoft.com/technet/sysintern...ssExplorer.mspx Also, giving a nice clean up utility a go, may boost your fps with 1 frame extra: http://www.ccleaner.com/download/builds.aspx