Google announced that a new ranking algorithm specifically for mobile search called "Speed Update" affecting a small percentage of queries. This is to force anyone one with a website to basically speed it up, else they will lose traffic from Google as they will be ranked lower in the mobile SERPs. As we know mobile users are increasing year on year so this is extremely important to maintain and grow your website traffic.
The update is coming in a few months and set to launch July 2018. This gives us all some time to make changes to our sites.
Google recommends you use the new updated PageSpeed report and tools like LightHouse to measure page speed and make improvements.
Google’s Zhiheng Wang and Doantam Phan wrote:
The “Speed Update,” as we’re calling it, will 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.
PageSpeed Insights report uses data from the Chrome Browser, this makes it difficult for smaller sites as there will not be that much data and can't accurately measure this. This means that the speed potion is not available for those sites. Obviously you can still use the optimisation reports, which is enough to improve your website.
Previously in 2010 Google said page speed was a ranking factor, this was just desktop and now with the new update due in July 2018 this will affect mobile users.
Personally I think this is an excellent move from Google, as everyone hates waiting for pages to load, especially on mobile when you want information fast!