Top navigation dropdown menus too slow to appear

I when you hover over a dropdown in the top navigation bar of this Wordpress theme (http://themeforest.net/item/teknium/full_screen_preview/77667), it’s incredibly slow. Especially in IE!

How can I speed that up, or even make it instant rather than cascading?

Please advise. Thanks in advance!

It is very well possible, but you'd better ask that in the Javascript forum because it is a JS-driven menu.