First : Optimize all the images. As per Google Page Speed (http://thebright.com), you can reduce another 233 KB, which will make your site fast.
Second : The issue that you mentioned - When you check the network tab in Google Chrome, clearly, there is some issue with the Cache Expiry header. Some how it is not setting Expiry header properly. So, every time you go to a page, it is loading the image once again even it was loaded previously. The current value that it is showing is : Expires:access plus 1 month
. Seems Apache HTTP Server is not handling this header properly.