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Optimize Your Largest Contentful Paint (LCP) Images with Jetpack Boost

LCP Image Optimization automatically identifies and optimizes the most important images on your website’s Cornerstone Pages. This feature analyzes your Cornerstone Pages, identifies their primary images (if applicable), and applies technical optimizations to make them load faster for your visitors.

LCP Image Optimization is available on both the free and paid Jetpack Boost plans. The free plan allows optimization for one Cornerstone Page, while the Premium plan supports up to ten.

What is Largest Contentful Paint (LCP)?

Largest Contentful Paint (LCP) is a Core Web Vitals metric that measures how long it takes for the largest visible content element—like a large image or headline—to fully load in a visitor’s browser.

A fast LCP gives the impression that your site is quick and responsive. A slow LCP, even if other elements load quickly, can make your site feel slow to users.

Why LCP Matters for Your Website

Largest Contentful Paint (LCP) is a Core Web Vitals metric that measures how long it takes for the largest visible content element to load on your webpage.

  • Visitors judge site speed based on how quickly the main content appears, not when the entire page finishes loading.  
  • A slow LCP makes your site feel sluggish, even if other elements load fast.  
  • A fast LCP makes your site feel professional and responsive.

Search Engine Optimization

  • Since LCP is a Core Web Vital, Google uses LCP as a ranking factor in search results.
  • Websites with good LCP scores (under 2.5 seconds) rank higher than slower competitors.
  • Poor LCP scores can negatively impact your organic search visibility.

What makes LCP slow?

Common causes of poor LCP performance include:

  • Large, unoptimized images.
  • Images without proper loading prioritization.
  • Missing responsive image techniques.
  • Slow server response times.
  • Render-blocking resources.

What is LCP Image Optimization?

LCP Image Optimization is a Jetpack Boost feature that identifies the most important visual elements on your key pages and applies performance enhancements to help them load faster.

It focuses on the largest image or background image visible in the browser window when a page loads—known as the LCP element. Optimizing this element can significantly improve your Core Web Vitals scores.

Enable LCP Image Optimization

To enable LCP Image Optimization:

  1. Go to Jetpack → Boost in WP Admin.
  2. Under Optimize your speed, expand the Images section.
  3. Turn on the “Optimize LCP Images” toggle.

Jetpack Boost will analyze your Cornerstone Pages and optimize the relevant LCP images.

How LCP Image Optimization works

Automatic Page Analysis

The feature examines your Cornerstone Pages to identify:

  • The largest visual element that appears in the viewport.
  • If it’s a standard or background image.
  • The optimal loading strategy for each device type (mobile/desktop).

Technical Optimizations Applied

For Image Elements:

  • Optimizes the LCP image through Jetpack’s Site Accelerator.
  • Sets fetchpriority="high" to prioritize loading.
  • Applies loading="eager" to prevent lazy loading delays.
  • Generates responsive images with srcset and sizes attributes.
  • Includes high-DPI display support.

For Background Image Elements:

  • Optimizes the LCP background image through Jetpack’s Site Accelerator.
  • Adds preload links in the document head.
  • Implements responsive background images using CSS image-set().
  • Applies device-specific media queries.
  • Uses CSS overrides to ensure optimal loading.

Understand LCP optimization status

After you enable Optimize LCP Images, Jetpack Boost analyzes your Cornerstone Pages. While this is running, Boost displays Jetpack Boost is optimizing your Cornerstone Page’s LCP…

When optimization finishes, Boost shows when the pages were last optimized and provides an Optimize link you can use to run the optimization again.

If Boost cannot optimize one or more pages, an LCP Optimization issues notice appears. Select the View details link to see the affected pages and the reason each page could not be optimized.

Troubleshoot LCP Image Optimization

For a full list of known issues and solutions, see Troubleshooting LCP Image Optimization in Jetpack Boost.

Still Need Help? 

Please contact support. We’re happy to advise.