In Photography version 4.3 or later. We added new progressive image loading option. Basically this option will help improving loading speed of your gallery, portfolio and blog templates.
Here is what is going on when visitor open gallery, portfolio or blog pages. If progressive image loading option is enabled. Page till load a tiny version of the image. At the moment, they seem to be requesting small JPEG thumbnails with a very low quality (e.g. 10%). The markup for this small image is returned in the initial HTML as an
<img/>, so the browser starts fetching them right away.
Once the image is loaded, it will replace smaller thumbnail automatically.
How to enable progressive image loading?
Navigate to Appearance > General > Image > Enable Lazy Loading Progressive Image After activating these setting you may need to regenerate your thumbnails