Core Web Vitals Are a Business Metric, Not a Dev Metric

It's easy to file Core Web Vitals under 'engineering hygiene' and move on. That framing undersells what the numbers actually predict: on the e-commerce projects we've measured, every 100ms of added load time correlates with a measurable dip in conversion.

On the Northwind Retail rebuild, we tracked Largest Contentful Paint alongside checkout conversion for six weeks before and after launch. The correlation wasn't subtle — conversion moved in the same direction as load time, almost step for step.

Search visibility is the second-order effect that takes longer to show up in a dashboard but matters just as much. Core Web Vitals have been a ranking signal for years now, and sites that ignore them are competing with one hand behind their back before a single word of content is considered.

The fix is rarely one dramatic change. It's usually a combination of image delivery, JavaScript bundle discipline, and font loading strategy — unglamorous work that doesn't show up in a feature announcement but shows up in the metrics that actually move revenue.