WooCommerce Speed Optimization

I do 2-3 massive sales every year and have a ton of traffic. On top of that my sales page is long and with lots of images, and this causes me a lot ot problems. Sometimes the site took 15 seconds to load even, affiliates complaint, etc. Someone recommended Numinix and I thought it was quite expensive but took the pluge anyway because something had to be done. Well, it is SO worth it. Best money spent, and now I purchase the service for every single sale.