I don’t think it’s caused by size: 3872px x 2592px (72dpi) has around 3.5Mb. Standard picture 1024×768 must be smaller than 5Mb.
If you are adding the watermark, don’t forget to save the picture without layers(export it to jpeg). Files with layers could be much larger(more Mb).
-- Michal, http://cakesdecor.com | My Facebook: http://www.facebook.com/michal.bulla
