On: The web sucks if you have a slow connection

[gnud]

It's too late to disable loading heavy things at that point - the loading is already started.

Do the opposite, start loading heavy things if the page loaded quickly.

A clean way would be to set one of two classes, connection-slow or connection-fast, on the body element. Then you could use those classes in CSS to choose the correct assets for background images, fonts and so on.

[neuland → gnud]

Well, I meant to leave the heavy things out of the HTML you send over to the browser and then inject them only if they can be loaded.

So, yeah totally agree with you. Should have been clearer.

[ComodoHacker → gnud]

>start loading heavy things if the page loaded quickly

...and not loaded from cache. You need a way to determine this reliably. AFAIK there's no way to determine this for the main page itself.