In many cases pages contains images there are only visible if someone scroll the page.
That is the simple trick i used here - these images are only loading if there coming in the visible area.
See the results of the simple testpage:
Original page is here:
In the results only 3 images are loading - 3 from 43 with a size of 720 x 326 px and total of 2,1 mb.
In the real world of internetshops with 80 … 120 small or middle sized images on a page the pagespeed jumps immediately to a very high score.