I think for various reasons, one should make pics small. For one: Often there are complaints about stolen art. High res big pics are at a higher risk to be stolen because they can be used for prints or other purposes. Second: Pics, that are to wide and/or high for the screen can not be viewed without scrolling. I think that does more damage to the image, than making it smaller and compressing it a bit. Third: This storage space is for free.... I raise the saturation and contrast a bit before the shrinking process to improve the final image. Then I make the image dimensions smaller. At last I use the option "save for web" to compress it with the lowest possible loss.