Large images and Largest Contentful Paint
Largest Contentful Paint, or LCP, measures when the largest qualifying visible content element is rendered. It may be an image or a text block. A large homepage photograph can be involved, but its file size is only one possible part of the delay.
Before you start
- Use a performance report that identifies the page's LCP element.
- Keep the original image and note the mobile and desktop versions of the page.
What to do
Identify the element before editing
Do not assume the largest file is automatically the LCP problem. A report may identify a heading instead of the hero photograph. Save the relevant result and ask which part of the loading sequence is slow so the proposed change matches the actual evidence.
Check the image's practical needs
If an image is involved, compare its delivered dimensions with its visible placement. A full camera original may be unnecessary for a modest banner, while a tiny compressed copy can look poor. Prepare an appropriate version and inspect the crop on a phone.
Review loading with the developer
Important first-screen images should not be needlessly delayed by an unsuitable loading strategy. Ask the developer to review resource discovery, priority and any blocking work. Do not turn every image into a high-priority download or copy performance settings without understanding the page.
Test the whole result
Compare a controlled before-and-after test and actually open the page. The image should appear clearly without a new layout jump or missing alternative text. If little changes, investigate the remaining bottleneck rather than repeatedly compressing the photograph until it becomes visibly damaged.
What to check
- The report identifies the element and the proposed fix addresses it.
- The image remains useful, sharp enough and correctly cropped.
- Performance testing and ordinary mobile viewing both inform the decision.
Sources and further reading
Platform features can change. Check the provider’s current guidance before changing a live service.