preload pagespeed insights for google ranking

Optimizing Largest Contentful Paint (LCP) with Image Preloading in PageSpeed Insights

Photo by Caio

Achieving a fast Largest Contentful Paint (LCP) is crucial for a good user experience and strong SEO performance. LCP measures the time it takes for the largest content element in the viewport to become visible to the user, typically an image or video. When PageSpeed Insights identifies an image, especially a background image, as affecting LCP, preloading these resources can significantly improve loading times. This post explores how to effectively use preload for images to enhance LCP and overall page speed.

Understanding the Importance of LCP

LCP is one of the core web vitals that Google uses to assess the user experience on a webpage. A faster LCP helps ensure that the main content of a page loads quickly, which can reduce bounce rates and improve user engagement. Images, particularly large background images, are often the largest elements on a page and can significantly impact LCP times.

How Preloading Images Improves LCP

Preloading is a browser mechanism that allows developers to hint to the browser about what resources it needs to fetch and process first. This is particularly useful for critical resources like large images that impact LCP. By preloading key images, you ensure they are loaded early in the page load process, which can prevent them from being delayed by the load of other less critical resources.

Implementing Preload for Images

Here’s how you can implement preload for images that are critical for LCP:

  1. Identify Critical Images: Use PageSpeed Insights to determine which images are affecting your LCP. Focus on large images, such as hero images or large background images, that are visible above the fold. Click on the LCP filter once you’re on the results page to get the specific images affecting your LCP score.
  2. Add Preload Tags: Once you’ve identified the critical images, you can instruct the browser to preload them by adding a link tag in the <head> of your HTML. For example:
   <link rel="preload" as="image" href="path/to/your/image.jpg">

This tag tells the browser that image.jpg is an important resource and should be loaded early in the page load process.

  1. Use Correct Attributes: Ensure that the as attribute is set to image to specify that you are preloading an image. You can also use the media attribute to specify conditions under which the image should be preloaded, such as screen size for responsive images.
  2. Verify Preload Effectiveness: After implementing, use tools like Chrome DevTools to ensure that the preloaded images are indeed being loaded early. You should also rerun PageSpeed Insights to see the impact on your LCP score.

Best Practices for Image Optimization

In addition to preloading, consider these strategies to optimize your images further:

  • Optimize Image Sizes: Compress images without losing quality to reduce their file size.
  • Use Modern Image Formats: Formats like WebP offer better compression and quality characteristics compared to traditional formats like JPEG and PNG.
  • Responsive Images: Use the <picture> element or srcset and sizes attributes in <img> tags to serve appropriately sized images based on the user’s device.


Optimizing LCP by preloading critical images can dramatically improve your website’s performance and user experience. By prioritizing the loading of LCP elements, you help ensure that your site’s most visually impactful content loads quickly, enhancing both perceived and actual performance. Always combine preloading with other image optimization techniques for the best results. With these strategies, you can ensure your site meets modern web performance standards, keeping both users and search engines happy.

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