Windows 7 has introduced a whole slew of issues centering around network performance. One particular area that Insight customers on Windows 7 have noticed is that Insight is slow to generate and display a list of files and folders in the various dialogs that displays file lists i.e. Open, Parts Library etc.
Select the Connections tab.
Click the "LAN Settings" button.
Uncheck the "Automatically detect settings" box.
UPDATE: Just to clarify, even though this post focuses on Insight, you should make this tweak for Windows 7 regardless, even if you use unmanaged Solid Edge as the tweak improves *all* WebDAV performance.