“We shaved 1.5 seconds off our LCP” does not get budget approved. Stakeholders nod and move on to the next agenda item, because they hear an engineering achievement and nothing they can fund. Budget follows the sentence “and that’s worth approximately €X per month.” The translation takes little work, but someone has to do it. Most teams skip it, then wonder why performance work keeps losing to feature work.

Why the connection stays hidden by default

Speed and revenue are causally linked, but they show up in different systems. Your Core Web Vitals live in PageSpeed Insights or a Real User Monitoring dashboard, and your revenue lives in GA4 or your CRM. No default setup puts them on one chart, so you see the correlation only if you look for it. Most teams look only after a director asks what the work gets them.

Start with a controlled comparison: the conversion rate of sessions with a fast LCP against the conversion rate of sessions with a slow one, on the same site over the same period, with traffic source held constant if you can. Most sites collect this data and never look at it. In a typical Foresight deployment we run this comparison during onboarding, before we touch anything, because the rest of the conversation depends on that number.

What “typical” looks like, and why you shouldn’t borrow it

On a typical Foresight deployment, average LCP moves from about 4.1s to 1.6s, and conversion rate rises about 29% in the same window. These figures are illustrative, taken from actual deployments, and promise nothing for your site. Your baseline LCP, traffic mix, funnel length, and average order value all change what a given speed improvement is worth. The same percentage lift produces a different euro figure on a site converting at 1% with a €40 average order value than on a site converting at 4% with a €400 average order value.

An industry benchmark tells you the effect probably exists. Your own sessions tell you what it’s worth to you.

The math that turns milliseconds into a budget line

With your own before/after (or fast/slow) conversion delta in hand, the rest is arithmetic that finance can follow:

  1. Monthly sessions × conversion rate lift = incremental conversions
  2. Incremental conversions × average order value (or lead value) = incremental revenue
  3. Incremental revenue, annualized, next to the cost of the fix

The third line puts performance work in the same currency as everything else on the roadmap, so finance can weigh it against feature work on equal terms.

Where this fits with what we do

We run this calculation with each Foresight prospect before we recommend anything, because a business case built on someone else’s numbers fails at the first skeptical question in a budget meeting. If you want the number for your own site instead of the industry average, an audit starts with this query on your own analytics data.