GIF yields a 3:1 file size compression while JPEG achieves 50:1 compression.
GIF dithering leads to larger file sizes
Aim to reduce file size
Reduce the bit-depth of an image by removing unused colors. Create the most economically
sized images you can to reduce download time. Always include height and width elements in
the <IMG> tag -- this allows the browser to allocate the space on the screen for the image.