I was wondering whether the real time scanner of NAV / NIS 2007 would scan ALL files or just certain extensions for example. I noticed quite some performance differences with Kaspersky and F-Secure when changing from the default (just certain extensions) to scanning all files (which actually makes them having a noticeable impact on system). If Norton does not scan all files, then it could explain some of its lightness. I know that for NOD and AVIRA I cannot really tell the difference between scanning all files or not. Thanks for your comments! By the way, which settings do you use / would recommend for the real time scanner? Is it really necessary to scan all files? Any known exploits that make misuse of this?