There are several website structural factors that can determine how searchable your site is, speed being one of them. In a world where we expect instant information, a website that that loads even only slightly on the slower side can deter a user. There’s also no point having a site that looks great but does not function properly on a Mac or PC.
The design of your site is important not only for users, but for search engines as well. Search engines today are smart, calculating a number of complex correlation data to determine the relevance of a site according to a search term. ‘Crawling’ through web content, search engines speed-read each and every page of content on your site, isolating the relevant ones to match a search term.