"It is unclear how many sites have already switched over to the mobile-first indexing process, but, when I asked Illyes to clarify what he meant by “a few sites,” he said a few relative to the Google index. So that could be quite a large number of websites."

"You have optimized every line of code of your site / mobile application, used all the techniques at your disposal to have the fastest loading time possible. Yet, users still complain about the slowness. Let’s learn to use different design techniques and UX to work performance also at the level of user perception."