Preload problem. HELP!

Hi all, I’m working on a site at the moment that loads in the sections as seperate .swf files. Each satelite .swf has a preloader which, for some reason, doesn’t kick in until its 70+% loaded.
Here’s the code I’m using.

Frame 1: percent=Math.floor(getBytesLoaded()/getBytesTotal()*100);
Output.text=percent+"% loaded";

Frame 2: if (percent == 100){

There are around 10 large(ish) images within the file but, despite the fact that the first three frames contain nothing but a dynamic text box, loading code and a white background, the bandwidth profile says the first frame is 216k. Even so,using the simulated DSL setting the preloader doesn’t appear until around 80% loaded. Why is this? I’m tearing my hair out here. Oh, before anyone asks, I haven’t ticked the ‘export in first frame’ option in any of the movieclips.