Support deferring the load of below-the-fold images and iframes on the page until the user scrolls near them. This is to reduce data usage, memory usage, and speed up above-the-fold content. Web pages can use the "loading" attribute on <img> and <iframe> elements to control and interact with the default lazy loading behavior, with possible values "lazy", "eager", and "auto" (which is equivalent to leaving the "loading" attribute unset).

Deferred content will start loading in when the user scrolls the viewport within a particular distance of it. The load-in distance depends on factors like the speed of the network, tuned such that content is typically finished loading in by the time it becomes visible.

https://groups.google.com/a/chromium.org/forum/#!msg/blink-dev/jxiJvQc-gVg/wurng4zZBQAJ

May be we will finally have much less buggy scripts doing similar thing. All normal browsers must have similar for long time.