Only a few weeks ago Netflix launched FAST, now it is Google's turn with a glorified version of Google PageSpeed Insights it seems. The tool measures how mobile friendly your website is and how fast it is loading for it's users.
It analyses your website and gives the design and loading speed a rating on a scale from 0 - 100. It looks at css, js and images to determine how long it takes to load the website on mobile and desktop. Additionally, they also provide an option to receive a detailed report with all their remarks and tips about your website.
Google says an average user leaves the site if it doesn't load on mobile within three seconds, so if your site takes much longer than that, you might want to check that out and try to get that down.
Your customers live online. When they need information or want to find a nearby store or product, they grab the nearest device. On average, people check their phones more than 150 times a day, and more searches occur on mobile phones than computers. But if a potential customer is on a phone, and a site isn’t easy to use, they’re five times more likely to leave.
You can give it a spin on https://testmysite.thinkwithgoogle.com.