You are using Windows Vista or Windows 7 to access WebDAV resources. No proxy server is between your client machine and the WebDAV resource. You may experience longer than expected delays when:
Opening a WebDAV folder
Copying files to or from a WebDAV folder
Changing from one folder to another on the WebDAV folder
When WebClient issues a WebDAV command, it checks for a web proxy server before issuing each command. When Auto-Proxy detection is enabled and there is no proxy server in the environment between the client and WebDAV resource, WebClient waits for the timeout of Auto-Proxy detection. Command completion will take longer due the wait for the Auto-Proxy detection timeout.
Confirm that there is not a proxy server between the client and the WebDAV resource. If there is no proxy server involved, de-select Automatically detect settings in the LAN Settings for Internet Explorer:
Start Internet Explorer.
Click Tools, and then click Internet Options.
Click the Connections tab, and then click LAN Settings.
De-select Automatically detect settings.
Click OK and test functionality.
Web Client performance lag respond