This translation has not been editorially reviewed yet. The German version is authoritative. Deutsche Fassung →
Checking LCP: when a page is "here" for visitors
Largest Contentful Paint measures when the largest visible element in the viewport has finished rendering — usually the main image or the headline. It's the value that comes closest to the subjective feeling of "the page is here".
- LCP is made up of several stages: server response, resource loading, rendering. A high LCP with a low TTFB points to a large or late-requested image; a high LCP with a high TTFB comes from the server, and image optimisation would change little about that.
- The most common single reason is a main image only loaded in afterwards by JavaScript. The browser only finds out late that it needs it at all.
- Important for context: LCP relates to the visible area at load time. What sits further down doesn't count — even if it's larger.
FAQ
Which element is the LCP candidate?
The largest image, video poster, or text block rendered in the viewport. Measurement tools name which one it was along with the value — without that information, you're optimising blind.
Why is our LCP worse on mobile than on desktop?
Because mobile is measured with a throttled connection and weaker processing power, and the viewport is smaller — often a different element is the candidate there.
Does a CDN help against a high LCP?
Only if the bottleneck is in delivery. If the server response is already fast and the image is requested late, a CDN won't shift anything.