One of the key features of this module is that it produces a display that is fully responsive. However this module does not natively re-size the raw source image files that are sent to the browser so that they themselves are responsive/adaptive to different device sizes. If we have a method available to adaptively re-size the source images for different devices we can save bandwidth when smaller screen sizes are used.
There are a lot of Drupal modules out there that already focus on this task of dynamically resizing source images (AIS, Picture, Responsive images and styles, etc.) so this task is all about identifying which of these modules will work best with Juicebox as opposed to building any new functionality for Juicebox.
It's possible that other users have already done this analysis and implemented Juicebox with source image resizing, and if so I'd love to hear from them. Either way I'd like to use this thread as a place to make some notes on the topic with the goal of adding some details the documentation and/or project page about this.