Largest Contentful Paint (LCP)
environmental
social
governance
direct
This metric measures the Largest Contentful Paint (LCP), which represents the render time of the largest visible content element in the viewport. It reflects how quickly users perceive a page as loading and usable, making it a key indicator for user experience and frontend performance.
In a Green Agile context, LCP connects user experience quality with energy efficiency. Slow rendering times often indicate oversized assets, inefficient loading strategies, or unnecessary data transfer — all of which increase energy consumption on both client and server side.
Classification
- Category: UX, Accessibility & Frontend Performance
- Measurement Frequency: per release
- Responsibility: Engineering Team
Impact
A low LCP value improves perceived performance and reduces user frustration, especially on low-end devices or slow networks. Because teams often set LCP as a release KPI or performance budget, it also supports governance by making performance and sustainability trade-offs explicit and measurable. Faster rendering reduces the time devices spend at high power states, contributing to lower energy consumption during page load. Improving LCP therefore supports both environmental sustainability and social sustainability by enabling accessible, performant experiences for a broad range of users.
Because LCP directly reflects frontend delivery efficiency, it is a direct-impact metric. It encourages teams to optimize images, fonts, scripts, and loading strategies, and to prioritize meaningful content over decorative or blocking elements.
Calculation
LCP is measured as a time-based performance metric, typically reported as the 98th percentile of observed page loads to capture worst-case user experience.
\[\text{LCP} = \text{Render time of the largest visible content element (98th percentile)}\]A value of ≤ 2.5 seconds is considered good according to common web performance standards.
Example
Assume real-user monitoring data shows the following LCP values for a product page over a release cycle:
- Median LCP: 1.9 s
- 75th percentile: 2.2 s
- 98th percentile: 2.8 s
Because the 98th percentile exceeds the recommended threshold, the metric indicates a performance issue affecting a subset of users. By optimizing hero images and deferring non-critical scripts, the team reduces the 98th percentile LCP to 2.3 s, bringing the page back into the good range.