On an iPhone 3G, try an album with 1000+ images and select an image before the "Loading..." message goes away.
Eventually it is going to crash in numbersForRow because assetGroup is not retained as it should be.
Try the version of ELCImagePickerController that I've branched and updated. I was having the same trouble as you in terms of getting large numbers of images to load. The version I have appears to be working pretty well. Hope this helps!