In 2015 web access from mobile browsers (smart phones and tablets) was approaching 50% of web page accesses.
In fact, 53% of visits are abandoned if a mobile site takes longer than three seconds to load. … We’ve actually seen that for every one second delay in site load time, conversions fall by 12%. Immediate need for flawless mobile experiences - Think with Google Test Your Mobile Website Speed and Performance - Think With Google
Mobile Friendly Pages