Speed had counted in desktop ranking since 2010. On 17th Jan 2018 Google extended it: "starting in July 2018, page speed will be a ranking factor for mobile searches".
Google set the scope narrowly. The Speed Update "will only affect pages that deliver the slowest experience to users and will only affect a small percentage of queries".
It applied "the same standard to all pages, regardless of the technology used to build the page". And relevance still won: "a slow page may still rank highly if it has great, relevant content".
Google offered no tool to say whether a page was affected. It pointed to the Chrome User Experience Report, Lighthouse and PageSpeed Insights instead.
The page experience update of 2021 later made Core Web Vitals, including loading speed, ranking signals in their own right.
