Make the most of HTTP/2
When HTTP was specified, websites were, by and large, simple affairs. Reestablishing a TCP connection for each resource was a rather mimimal overhead when taken in context. As page complexity increased, steps were made to eliminate protocol inefficiencies. This resulted in an upgraded HTTP protocol called HTTP/2, which lets the browser and the server recycle an already-established TCP connection in an attempt to reduce latency and overhead. Further information on HTTP/2’S technical benefits can be found at http2.github.io/
— while Github hosts the page, its contents are maintained by the IETF and contains all kinds of valuable information.