Yeah when clicking buttons the navigation menu is messed up in Firefox. Just some minor flaw though, can't classify it as 'heavy' . High resolution images could be loaded way faster when saved in a much lower resolution. There are a few other things not quite right but all minor.

If you want a perfect website that matches the global standards, try to let your site pass the w3c.org html validator: http://validator.w3.org/

It's a nice idea hope you wont get problems with using acknex in the name, but I doubt it.