Website Load Time Optimization

Our website [login to view URL] started experiencing extremely slow load times. No major site updates have taken place to cause this anomaly. We need an expert to find the root cause of this problem and get the site back to loading in 4-5seconds. Here is a screen capture showing the home page (and simple jquery slide show taking 50 seconds to load) then the products grid page taking another 45 seconds to load. (using chrome as the browser), [login to view URL]