I would too if it took 15 seconds to see any content. But, if you can get the readable content to load within a couple of seconds and then while the user is reading the rest of the page is loading, then you've accomplished your goal. Typically the visitor is there for information.
In a graphics environment, like the one mentioned above, the use of thumbnails is excellent advice.
Note: The browser renders the code from top to bottom. If you've got a bunch of markup sitting there right after your <body> tag then it needs to load all of that first. Again, the goal is to position your content as close as possible to the opening <body> tag to avoid delays.
Very few graphically appealing pages out there in the 5-10k range. ;)