Users of the iPhone will notice that the eFlashCards use a lot of space on their device. Unfortunately, this is a "feature" of iTunes/iPhone that we cannot change. Here is the information we found about this in an Apple support forum:

This issue with the synced photo size is a tricky one. The photos are "optimized" by iTunes before being transferred to the iPhone, but they are not being optimized for file size. Rather, they are being optimized for display speed. Specifically, each photo, which is typically stored on your Mac as a compressed JPG file, is being converted to 640x480 pixel raw "555" (16 bit per pixel, 5 bits per channel) bitmap format. Now each photo takes up about a half a megabyte of storage space regardless of the original size on your Mac.
I believe this is so that the images in the Photos application can be displayed rapidly with no delay when flicking your finger between images.
To get around this weirdness, I would recommend using a 3rd party App Store app such as File Magnet for storing your JPGs. These file viewing apps will store your images in their native format.