Google recently announced that they will be placing emphasis on mobile loading times for search rankings https://searchengineland.com/google-speed-update-page-speed-will-become-ranking-factor-mobile-search-289904
I decided it would make sense to test some of my sites at https://testmysite.withgoogle.com/intl/en-gb and most did pretty well, but one in particular done with Blocs performed poorly. In reality, the page is not especially slow loading on my smartphone, however I suspect Google is including time for animations and carousel images to load in the background, which begs the question whether we should eliminate or heavily reduce the number of animations on our sites for mobile devices?
It strikes me that Google is taking a somewhat unsophisticated approach to their testing, but they provide results on what percentage of visitors is likely to abandon a site if it is too slow loading on a 3G connection. Presumably this will also form a basis for their rankings.