If you have light menu pages but heavy graphics on pages deeper into the site, sneak a graphic or two into the user’s cache while someone is reading your home or menu page.
To do this, set the graphic’s dimensions to zero(so it’s not visible) by putting the following tag anywhere in your HTML document:

If users linger on the menu page long enough for the image to load, it will be present in their caches when they proceed to the next page and thus will appear immediately.