The hover behavior above is governed by the “Display file size information in folder tips” setting on the View tab in Folder Options: Extend the scenario from the local machine and add in users who are browsing through a directory structure across the network and the performance hit would grow exponentially. May be several levels deep and consist of thousands of files and folders. This would create significant processor overhead – especially if you think about scenarios (home folders for example), where the nested directory structure

Every time you navigate through a folder structure in Windows Explorer, the OS would have to perform a recursive scan of the subfolder structure within each folder to get the file and folder sizes and add them up. The primary reason why the Windows UI does not provide this functionality is performance. You can view the size of folders by hovering over the folders in Windows Explorer (as shown below): That question is, “Why can’t I see the size of folders in Windows Explorer?” The simple answer is that the behavior is by design. Today’s post is a very short one, but it does address one of our most common Shell / Windows UI questions. First published on TECHNET on May 08, 2009

Folder size program