Blazy is a lazy loading library. It's great for sliders or pages with lots of images.
Here are some issues that are worth tracking:
Other lazy loading modules
https://www.drupal.org/project/lazy
https://www.drupal.org/project/image_lazy_loader
https://www.drupal.org/project/lazyloader
https://www.drupal.org/project/sirv
https://www.drupal.org/project/lazy_image_style
https://www.drupal.org/project/lazy_loading_formatter
https://www.drupal.org/project/blazyloading
https://www.drupal.org/project/blazy_blurry_placeholder
https://www.drupal.org/project/lazyload_images
https://www.drupal.org/project/fancyload
https://www.drupal.org/project/media_lazy_load_formatter
Module page
Stability
Stable