I change the speed like this.
<script type="text/javascript">
$(document).ready(function(){
$.colorbox.settings.slideshowSpeed = 4500;
$(".example1").colorbox({rel:'slideshow1', slideshow:true});
});
</script>
Colorbox uses the order that the html elements are in on your page to determine the order of the slideshow. Because VSD uses absolute positioning the order of the images appearing in the slideshow is usually the order they were added to the page. What you could try is placing all the images on a separate page, that has you colorbox code at the head of the page for testing, one at a time in the order you want them to appear. Their actual position on the page with VSD should have no affect. It's the order you add them to the page. Once you get them working properly on this page select them all and hit ctrl +c then go to the page you want the gallery on and hit ctrl + v.