I've been debating a lot on this and I strongly believe that website loading speed is the most crucial aspect of an eCommerce web design. Think about it; you want more customers and you want them to make a purchase from you, right?
However, if your eCommerce web design is really slow and takes more than 10 seconds to load a single page, you'll face a higher bounce rate. This means fewer sales at the end of the month. So while designing your website, ensure that the website loading speed is optimized properly.