Core Web Vitals are three metrics that measure a page's user experience. LCP measures load speed, INP the response time to an interaction, and CLS the shifting of the layout. All three directly affect a campaign page's conversion.
The three metrics and their thresholds
According to Google's definition on web.dev, the thresholds considered good are these.
LCP, the appearance of the page's largest content element. It should happen within 2.5 seconds.
INP, the response time to a user's click. It should be 200 milliseconds or under.
CLS, the amount the layout shifts while the page loads. It should be 0.1 or under.
The measurement isn't taken from a single visit. The assessment is made at the seventy-fifth percentile of page loads, and mobile and desktop are read separately.
The part that concerns the marketing team
On a landing page that buys traffic with an ad budget, these three numbers determine the return on every paid click. On a slow-loading page the visitor leaves before seeing the form. On a page whose layout shifts, the user hits the wrong button.
There are three most common causes: uncompressed images, images and ad slots with no dimensions set, and third-party scripts running at the top of the page.
These three metrics are directly tied to ad tags. Every measurement script added at the top of the page keeps the browser's main thread busy and inflates the INP value. The list of tags added for a campaign is the first place to look when investigating a performance problem.
The measurement shouldn't be done by one person. When design, development, and marketing aren't looking at the same number, the turn to fix it never falls to anyone.
The pre-launch check
Running an audit on the address before a campaign page goes live catches these three problems. Web Analyzer audits any address under SEO, performance, and accessibility headings, and the items it surfaces enter the Task Management board as tasks. The modules the marketing team uses are on the Marketing Teams page.
Here's the limit: Web Analyzer measures by testing the page at that moment. For field measurement calculated from real-user data you have to look at Google's own tools — the lab result and the field result don't always come out the same.
The order of fixes after measurement is set too. Shrinking image sizes gives the fastest gain on most pages; script cleanup comes second.
How width testing is done sits in the responsive design breakdown.
FAQ
Do Core Web Vitals affect ranking? Page-experience signals are used in search ranking. They don't replace content relevance; they separate otherwise-equal content.
Which device should I measure for? Mobile and desktop are measured separately. If most traffic comes from mobile, the priority is the mobile values.