Hi
just a suggestion - I do not know if it works:

have you tried to include your specific css background images in your templates html - by this I mean take them in one by one with a normal img tag but with a style of display:none;
then in theory they should be loaded to the cache of the browser - so when they are called by the css with their final styling rules the browser should be aware of these files already and no need for loading them...

so something like:
<img src="/yyyy/yyyy/nav-dot.gif" style="display:none;" />
<img src="/yyyy/yyyy/leftpane-bg.gif" style="display:none;" />
and so on...
somewhere near the top of the html of your template file

Might wanna give it a try (of course if you have a lot of these this might slow you down even more)

otherwise I would guess the aproach would be to force the slideshow to wait rather than try to get the css more fast... but I am not a programmer...

Cheers

Hm.
Unfortunately this doesn't work.

I can get the images which are used for the backgrounds to load first, which I've confirmed by leaving them visible as a test.
However, they won't display in position where the background style attribute says to untill after the slideshow images are loaded.

Anyone else have any good ideas?