A new report by Radware finds that "of the top 100 retail websites, the median page has grown 67% in just one year and many are failing to leverage advanced techniques to help accelerate their pages .. use of images is one of the single performance drains, as most site owners are not taking advantage of image optimization techniques that can dramatically improve both real and perceived load times
.. The median top 100 ecommerce home page takes six seconds or longer to render its primary content to online visitors – a 27% slowdown over the past year. This render time is more than twice as slow as the ideal user experience of three seconds or less. Only 14% of the top 100 retail sites were able to deliver an optimal user experience. 17% took ten or more seconds just to be become interactive.
See "One Year Later – Websites are Going Nowhere Fast – New Radware Research Reveals Retailers Still Make Same Web Performance Mistakes" - here.