Review AJAX Pages & Advise ways to Speed Up or Improve

We have a cart written in AJAX. It appears to be well written but sometimes it has slow re-draw. My programmer is excellent but I always like to get additional opinions from other experts. We are looking for any advice or suggestions to help us speed up the load time or functionality. The cart can be found by Step 1 - go to: [login to view URL] Step 2 - Select the button 'Build Your Menu' You will land on : [login to view URL] This is the page in AJAX. Experts only. Thanks for looking.