Users care about the speed of a page. Starting in July 2018, page speed will be a ranking factor alongside other SEO factors for mobile searches. This signal was focused on desktops, but from this month, page speed is a ranking factor for mobile searches on Google.
“The “Speed Update,” only affect pages that deliver the slowest experience to users and will only affect a small percentage of queries. It applies the same standard to all pages, regardless of the technology used to build the page. The intent of the search query is still a very strong signal, so a slow page may still rank highly if it has great, relevant content.”
The following are useful tools and reports: