When user opens a web page, browser sends multiple requests to the web server to get different components of the page resulting in numerous connections between browser and server. Each connection to the webserver is usually a short lived connection and puts overhead of connection management on web servers. Also, technologies like AJAX relies on keeping multiple connections open between the browser and the server. Each connection consumes server resources – memory, CPU, bandwidth etc. thus reducing the server capacity to serve new clients.
HTTP 1.1 lets a browser sends multiple requests over a persistent connection to a server, eliminating some overhead. But content providers turn off this feature because multiple long
lived sessions from large number of clients can consume a lot of resources on the server and can lead to DoS for other clients.
To learn more and to read the entire article at its source, please refer to the following page, Connection Multiplexing in NetScaler- The Citrix Blogs