HTTP Pipelining
www.guypo.com/mobile/http-pipelining-big-in-mobile
From the page
Saved with the link. Notes from 2007 to 2016 are mostly the page's own words, so this is probably an excerpt.
HTTP pipelining has been around for quite a while since HTTP/1.1 was introduced. When using pipelining, an HTTP client may send multiple requests on the same connection, without waiting for the server to respond. Doing so practically eliminates the round-trip time (RTT) overhead of all but the first request, especially if the server responds quickly.