I've talked to Lee about this..
But lets say you create a new site, and you have 16 textures to replace the original set, each time you right click to replace a texture the image bank is cached so if you replaced 16 in on go you have 15 textures cached which are never used
Also these cached textures end up in a built game, they are replicated 3 times
Its easy to test, look at the size of ebebank\default and \levelbank\testmap also \levelbank\testmap in a built game, I built cartoon Antics with version 1.131 its was 299 MB I built a simple ebe cube scene its over 1gb, the cube scene takes 16 seconds to load the cartoon one takes 19
I'm just saving Cartoon Antics again..... its now 777meg because it has the cached ebe files in levelbank\testmap