To quote Bruce...
At the moment, as you know, when you have a popup form, or browse lookup or something, then a small container
is generated as a "stub". So if you then open the form, the stub immediately appears, at which point the server generates
the contents of the form.
Front-Loading reverses this a bit. With front-loading the whole form is generated into the stub when the page is created. This makes
the first page slower, and bigger. However the app can be "more responsive" later on because _only_ the data is then being retrieved from
the server. So the packets "later on" are smaller, and faster.
This is where the term "front loading" comes from. By moving more work to the "front" you're able to save work later on.
Front-Loading though isn't just an end unto itself. It's a stepping stone towards something quite interesting. For example, if we generate
the whole app using popups we get a so-called "single page application". In this sort of app there is only one actual html page – and
after that all the interactions with it are these small Ajax packets. And (at least in theory) this large dynamic page could be cached.