In addition to allowing you to reference script files
directly using a <script> element, ASP.NET 4.0 will make it easy to use
the CDN from ASP.NET Web Forms applications that use the
<asp:scriptmanager/> server control.
The ASP.NET 4.0 <asp:ScriptManager> control includes a
new property named EnableCdn. When you assign the value true to this property,
When you enable the CDN with the ScriptManager, your
the System.Web.dll or System.Web.Extensions.dll assemblies from the CDN
for controls like TreeView, Menu, etc).
This provides a nice end-user performance improvement, and
means that users accessing your ASP.NET website won’t need to re-download these
files if they have visited another ASP.NET website that uses the CDN.