Opening a specific folder (windows explorer) from HTML URL

[costumxer]

I am in the process of building the internal site (ASP) for a website that handles applications for mortgate loans.For each application, there's a folder on the server that contains unique attatchments linked to the application. A wide spread of formats for the attatchments leads to my boss asking me to simply make a link that opens said attatchment-folder per application.Using file://servername/foldername/ works, but it takes AGES after clicking it before the actual folder opens. Any more efficient way of doing this?