It's this: https://googleblog.blogspot.co.uk/2015/10/introducing-accelerated-mobile-pages.html?m=1
That's interesting. I'd heard about this but didn't put the two together. It's only on some pages as well.
@Well_is_it started
London Fixed Gear and Single-Speed is a community of predominantly fixed gear and single-speed cyclists in and around London, UK.
This site is supported almost exclusively by donations. Please consider donating a small amount regularly.
It's this: https://googleblog.blogspot.co.uk/2015/10/introducing-accelerated-mobile-pages.html?m=1