My personal website has been dying a slow death, not because of the fancy graphics I use on it but because I'm stuck on shared hosting with 100+ other websites (1and1). That alone can make the difference. To download 100K to 300K isn't a big deal now days.
Also, for instance try tallying up all of Facebook's JS, CS + HTML files, and you'll discover the site clocks in over 1MB. Now consider how fast the pages on the site load (super fast) See the difference how your site is hosted can make?