Official Virus Scanning Recommendations for Windows 7 from Microsoft

Most of the anti-virus software out there, if not all of them, have the setting that allows you to exclude some of the folders or files from scanning. In some cases, certain folders have to be excluded from virus scanning process, some even requires to be excluded from the real-time protection.

Here there is a KB document on Microsoft support having some recommendations that may help you protect a computer that is running Windows server 2003, 2008, 2008 R2, Windows 2000, XP, Vista, and 7 from viruses. Basically, there are two type of files,

Do not scan the following files and folders. These files are not at risk of infection. If you scan these files, serious performance problems may occur because of file locking.

Microsoft windows update or automatic update related files

• The windows update or automatic update database file, datastore.edb, located in the following folder:
  %windir%\softwaredistribution\datastore
• The transaction log files, Edb*.log, located in the following folder:
  %windir%\softwaredistribution\datastore\logs

Group policy related files

• Group policy user registry information, NTUser.pol file, located at:
  %allusersprofile%\
• Group policy client setting files, registry.pol file, located at:
  %systemroot%\system32\grouppolicy\

Make sure following these guidelines when setting up anti-virus program on your computer to not only protect from virus but also reduce the potential performance problems as well.