Okay, I missed that "last" part. You could pre-load your images then, and the text should be fast. I'm guessing you could load the banners as hidden/invisible, then make them visible on a timer, but I wouldn't be the one to ask about the code itself. If all else fails, just host the banners on a really slow server
If the banners are actual images then you could do a simple image switch, otherwise you'll have to execute the banner script from within the pause. You should make sure the lack of banners when the page first loads doesn't force any of the contents to shift when they do load.