In 2010, Google did something very different. Google announced website speed would begin having an impact on search ranking. Now, the speed at which someone could view the content from a search result would be a factor.
While Google has been intentionally unclear in which particular aspect of page speed impacts search ranking, they have been quite clear in stating that content relevancy remains king. So, in other words, while we can demonstrate a correlation (or lack thereof) between particular speed metrics and search ranking, we can never outright prove a causality relationship, since other unmeasurable factors are still at play. Still, in large enough scale, we make the assumption that any discovered correlations are a "probable influence" on search ranking and thus worthy of consideration.
For more info:
https://moz.com