Originally Posted by GeoffR
For many of my epubs the cover takes up more space than the text already. Add a few images and the text often accounts for less than 10% of the epub filesize. The size of the cover and other images will just keep increasing as screen resolutions increases.
That's just very poor formatting by the publisher. With minimal knowledge anyone can run the cover through a graphic program and compress it correctly so you don't see any difference in the quality. There's no reason a cover for an epub needs to be over 100kb in size, and most of mine are well below that.
Most other small images for fancy chapter headings or dividers are usually under 10kb each. Again, if done properly to not waste space for no reason.