The History of Core Web Vitals

"Core Web Vitals measure user experience by assessing a website's performance. This write-up is a history of how Core Web Vitals came to be based on my recollections from our work on it at Google from 2014 onwards. The initiative saved Chrome users over 30,000 years waiting with businesses seeing revenue and user-engagement lifts through optimizing for it, inclusive of 2025."

"In 2023, the collective effort to optimize Chrome and websites across the ecosystem saved users a staggering 12,000 years of time, as measured by Core Web Vitals. Thanks to Annie Sullivan for her analysis showing this. The momentum grew significantly in 2024, with that figure nearly tripling to an estimated 30,000 years saved. This massive impact translates directly into a better, faster, and more responsive web experience for millions of users around the globe every day."

"Origins and motivation: from AMP to open web metrics For years, Google emphasized speed and user experience as core principles of the web. Google's Chrome team often repeated that "speed has been one of Chrome's core principles since the beginning" yet many sites still delivered sluggish experiences[1]. In 2010, Google Search began using site speed [2] as a lightweight ranking signal on desktop, reflecting an early view that faster pages create better outcomes for users and businesses alike. The signal was intentionally modest, but it put performance on the map for SEO."

Core Web Vitals measure web user experience using metrics such as Largest Contentful Paint (LCP), Cumulative Layout Shift (CLS), and Interaction to Next Paint (INP). Work on Core Web Vitals at Google began around 2014, building on earlier efforts to prioritize speed and user experience. Google Search used site speed as a lightweight ranking signal starting in 2010, and AMP emerged around 2015 to address mobile performance. Collective optimizations delivered measurable results: an estimated 12,000 years of user time saved in 2023 and about 30,000 years in 2024, with business revenue and engagement lifts tied to these improvements. As of September 2025, 53% of origins had good LCP, CLS, and INP per CrUX data.

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