With images making up a whopping 65% of all web content, page load time on websites can easily become an issue. Even when properly optimized, images can weigh quite a bit. This can have a negative impact on the time visitors have to wait before they can access content on your website. Chances are, they get impatient and navigate somewhere else, unless you come up with a solution to image loading that doesn’t interfere with the perception of speed.
Five Techniques to Lazy Load Images for Website Performance — SitePoint