Lazy loading will not load image until it becomes visible to a user. Pixboost.js supports lazy loading for both responsive and non-responsive images. To enable lazy load you need to add data-lazy attribute to <div> or <img> elements.
Lazy loading in Pixboost.js implemented by using 3rd party library lozad.js. In order to make it work, you'll need to use pixboost bundle (see Usage section) or add the library with polyfill for the Intersection Observer feature if you want to have support in all browsers: