Why you need to know your site’s performance plateau (and how to find it)

April 24, 2025

Bar and line chart showing Largest Contentful Paint (LCP) in seconds vs. number of sessions and conversion rate. Bars peak around 1s LCP and decline after; the blue conversion rate line drops steadily, plateauing around 2.8s. Text annotation notes "performance plateau starts at 2.8s".

Have you ever asked yourself these questions?

“I made my pages faster, but my business and user engagement metrics didn’t change. WHY???”

“How do I know how fast my site should be?”

“How can I demonstrate the business value of page speed to people in my organization?”

The answers might lie with identifying and understanding the performance plateau for your site.

What is the “performance plateau”?

The performance plateau is the point at which changes to your website’s rendering metrics (such as Start Render and Largest Contentful Paint) cease to matter because you’ve bottomed out in terms of business and user engagement metrics.

Source: SpeedCurve | Why you need to know your site’s performance plateau (and how to find it)

Performance is well know to be highly correlated with measurable business outcomes–until it;s not. But why?

Tammy Everts discusses the performance plateau.