For all the criticism I lay on Safari, and Apple because of it, here is one instance where they are leading the way and in a style we should cheer.
Every browser has a "rendering engine", which is what actually decides how to interpret the code to display the page. It is a rather large set of processes. The idea of having a separate "loading engine" makes a lot of sense and while Apple is not calling what it is doing with Safari a loading engine, I believe that is a good way to describe it. As far as I know, no one else is actually doing things this way......yet.