Speed up Oscommerce Site

I just had my site built and I did a speed analysis on this page and it showed my site loads very slow due to mostly size of file or images. [login to view URL] I'm looking to bring on an expert to speed up my site and make certain they are fully compatible with all browsers. Image optimize,css etc... Also need to fix a couple small things left by previous designer. 1. No "sign off" option for customer. 2. Coupon installed but not working properly. That all. The site is fully functional currently.