> The ability for PJPEGs to offer low-resolution ‘previews’ of an image as it loads improves perceived performance – users can feel like the image is loading fa

> The ability for PJPEGs to offer low-resolution ‘previews’ of an image as it loads improves perceived performance – users can feel like the image is loading faster compared to adaptive images. My understanding was that progressive JPEG actually feels slower, since users are less sure when the image has finished loading, and are thus best avoided in most cases.