Assume that you run a query that contains many range query words that begin with the same letter in Microsoft SharePoint Foundation 2010. In this situation, the query is not completed and W3wp.exe consumes excessive memory.
To resolve this issue, apply the following update:
2596484 Description of the SharePoint Foundation 2010 hotfix package (Sts-x-none.msp): October 25, 2011
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.