You archive some SharePoint files to a cheaper form of storage, such as a magnetic tape handler. Then you take those files offline. However, when you perform a full crawl for the remaining online files, performance is very slow.
To resolve this issue, apply both of the following updates:
970946 Description of the Windows SharePoint Services 3.0 Cumulative Update Server Hotfix Package (Sts.msp): June 30, 2009
970948 Description of the SharePoint Server 2007 Cumulative Update Server Hotfix Package (Coreserver.msp): June 30, 2009
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.