Do spend more effort reducing the storage size of your graphics the wider the audience you hope to appeal to. Don't use persistent animations or blinking text. You can take some simple steps to have your documents load faster on the browsing end, and thus stand a much greater chance of being read.
Many people deal with slow connections by turning off default display of images.
For a browser to display the text on your page, it must know how much space to leave for images. The most common way to figure this out is for the browser to wait until the whole image is transmitted to figure out how big it is. While the browser is waiting for your image to arrive, it displays a blank page. As a rough rule of thumb, you might want to do this with any image larger than 1 K in size. You might use this to have a browser enlarge an originally small image.