Develop an e-commerce website using Slim framework, where customers can browse products, search for items by different criteria (e.g. name, category, price), add them to cart, and purchase them online. The website should have clear navigation, fast loading speed, and a responsive design that adapts to different screen sizes. It should also include a secure payment gateway, order tracking system, and user authentication features. Ensure that the website is optimized for SEO and meets web accessibility standards.
This prompt doesn't seem malicious.