Tech Issue #2 - CAN JAVASCRIPT SPEEDS THINGS UP? If I understand correctly, some have said Javascript in the browser can reduce or eliminate the HTTP overhead

Tech Issue #2 - CAN JAVASCRIPT SPEEDS THINGS UP? If I understand correctly, some have said Javascript in the browser can reduce or eliminate the HTTP overhead and dramatically reduce both data transfer and bandwidth requirements. Is this true? I don't know how to do this but I welcome a simple explanation that illustrates how it might work. Right now I'm thinking that HTTP headers still need to be sent upon each request and they will use much more bandwidth than the data itself. Is the ultimate solution to find a way to transfer data without constantly opening and closing HTTP connections?