A Detailed Guide on How to Improve Website Lighthouse Scores


You need a high-performance website to deliver an enhanced user experience. However, how to ensure that your website offers such an experience? Improving the website performance requires measuring specific parameters, including the loading speeds and others. Google Lighthouse is a tool that you can use to measure website speeds and other important parameters. 

For example, Google recommends a web page load within 1-3 seconds, making the loading speed essential. Lighthouse helps analyze loading speeds and aspects like content display rate, delays in layout shifts, and more. We will discuss ways to optimize website Lighthouse scores and improve user experience. Let us begin by understanding the Google Lighthouse tool.

What is Google Lighthouse?

Google Lighthouse is a free online tool that helps measure website performance. You can use it to generate a Lighthouse report. It will show different parameters and scores of website performance. These parameters are according to Google’s page experience update and core web vitals.

Lighthouse report breaks down web page user experience, helping businesses understand how the website performs. In addition, as Lighthouse is a Google tool, you can leverage it to understand how the website performs in search engine rankings.

Each Google Lighthouse report consists of five key parameters,

  • Performance
  • Accessibility
  • Search Engine Optimization
  • Best practices
  • Progressive web app 

The Lighthouse report has a 1-100 score for each parameter, which can vary depending on Google ranking criteria changes. Now that we know what Google Lighthouse is let us understand how to use it for a website audit.

How to Use Lighthouse to Audit a Website?

Auditing your website is accessible with Google Lighthouse. You only need to paste the URL into the tool to generate a report. It has several critical parameters like First Contentful Paint(FCP), Largest Contentful Paint(LCP), Speed index, Time to interactive, Cumulative Layout Shift(CLS), etc.

You can access the Lighthouse tool through the official website. Once you click on the analyze button, the tool will generate website Lighthouse scores. Next, let us understand how to assess the report for website performance.

Lighthouse Report and Metrics to Look

Lighthouse reports have four primary metrics that you will notice right at the top, 

  • Performance
  • Accessibility
  • Best practices
  • SEO

Website performance in Lighthouse report.

The performance part of the report shows website lighthouse scores for metrics like LCP, FCP, and others. Each metric helps measure a different aspect of page experience.

  • Largest Contentful Paint (LCP) helps measure the time the largest image or text takes to render on the web page. Google recommends that the LCP score is within 2.5 seconds.
  • First, Contentful Paint (FCP) measures the delay between the time your web page starts loading and the first part of the content renders. FCP score should be between 1.8-3.0 seconds.
  • Cumulative Layout Shift (CLS) measures sudden changes in the website’s design layout. The ideal CLS score needs to be less than 0.1. However, especially for eCommerce websites, higher CLS can mean accidental clicks leading to a bad user experience.
  • Time-to-interactive helps measure how long your page will take to become fully interactive. For example, a page can be called interactive when the useful content renders, and the page responds to the user’s interaction within 50 milliseconds.
  • Speed index measures how quickly a page populates all the content. In other words, a user can see a web page’s visible parts over time.
  • Total blocking time measures the time taken by a website between FCP and TTI. The main thread is blocked to prevent input responsiveness due to a lengthy task. The long task must take at most 50 milliseconds.

These are some important metrics you can optimize to improve website Lighthouse scores. In addition, the report provides more insights into the website’s performance.

How to Test Speed and Performance Using Lighthouse

Each part of the Lighthouse report provides insights you can use to improve website performance. For example, the performance section includes insights on website speed and image resources.

Similarly, SEO helps measure your website’s mobile-friendly, along with technical aspects like Meta, site crawling, structure, etc. Further, website Lighthouse scores also show important responsiveness and page elements insights. However, analyzing each section becomes key to optimizing the website performance.

How to Analyze the Lighthouse Performance Report?

Once you get the report from the Lighthouse tool, the analysis process will require the assessment of different metrics. 


The accessibility of the website is not just about speed, but it is about users’ access. Therefore, audits for accessibility are different from the performance part as there is only pass and fail with no scoring aspect. 

Accessibility assessment is provided in percentage, considering whether your content complies with Web Content Accessibility Guidelines (WCAG). It also helps assess whether your website complies with the Web Accessibility Initiative – Accessible Rich Internet Applications Suite (WAI-ARIA).

Best practices

Best practices include website lighthouse scores, which help improve the site’s overall performance. For example, it shows whether your website has secure database connections like JavaScript libraries and site have an SSL certificate from a trusted brand like RapidSSL certificate, GeoTrust SSL certificate, or DigiCert SSL certificate.

There are types of best practices for which the website Lighthouse scores are given out of 100. Now that you know the parameters, you can analyze them in the Google Lighthouse report, so let us understand how to read them.

How to read the scores of the Performance section?

We already know what metrics you will find in the result of the performance section. However, reading them and assessing the data are two different things. So let us understand the weightage for each of them to create a clear picture of website performance. 

  • FCP has a weightage of 10% of the total performance score and is the perceived website speed for users.
  • Speed index also contributes 10% of the total performance score with an ideal score of 75, equivalent to 4.3 seconds.
  • LCP has a weightage of 25% on the total performance score
  • Cumulative Layout Shift contributes 15% to the performance score. But in real-life scenarios is more impactful for user experience
  • TBT is one of the most significant contributors, with 30% of the total performance scores
  • TTI, or time-to-interactive impact of 10%, is one of the most important metrics to improve the website experience.

Each of these metrics has a hyperlink on the report, which you can click to understand how to improve website Lighthouse scores. Now, you know how to use the Google Lighthouse tool and read the report. Therefore, it is time to leverage it and improve its performance.

How to Optimize Your Lighthouse Performance Score on WordPress

Google Lighthouse scores will help understand the website’s technical aspects that hinder user experience. You can leverage these insights to improve website Lighthouse scores through WordPress optimizations. 

Use caching 

LCP scores depend on how fast the critical content renders your web page. Unfortunately, most organizations struggle to render faster for many reasons, including server issues, network problems, and more. 

Here the data availability and faster rendering are of significance. Caching allows you to create a local version of the website data that you can use to render the content faster, increasing LCP scores. There are many WordPress plugins and tools like Hummingbird, WP Rocket, WP Fastest Cache, and LiteSpeed Cache, which you can use for caching purposes.

Optimize the content

Website content includes images, texts, videos, and more. You must adjust fonts, photos, and other content to improve website speed. For example, you can ensure that no unnecessary CSS or JavaScript files are blocking the main content leading to increased LCP. Here are some tips to optimize content,

  • Lazyload images to optimize the user experience and improve website Lighthouse scores
  • Remove unused CSS and JavaScript files to optimize TBT and TTI scores
  • Minify JavaScript and CSS files by removing unnecessary characters from the source code without altering its functionality
  • Leverage a content delivery network to ensure optimized content delivery across servers if you operate in many countries.
  • If you add images manually, ensure that you have the correct dimensions, as it will improve CLS.
  • Reduce the time for JavaScript execution to ensure better speed index and FCP.

Enable PWAs

The tips we discussed above will help you improve the performance of your existing website on WordPress, but if you want to add new features, PWAs can help. It will help you drop bounce rates, increase visibility and improve user experience. You can use the “Accelerated Mobile Pages” plugin released by Google to boost the visibility of your website. 

Further, PWAs will help you leverage cache assets for a long time and use push notifications and web page caching. The best part of PWAs is how users can download your website as an application on their device and use it offline with limited function. 


Lastly, it becomes imperative for any website publisher to check the site’s health through tools like Google Lighthouse. It allows businesses to understand different aspects that affect user experience and search engine rankings. Here we have discussed how you can use, read and analyze website Lighthouse scores with some best practices. However, which approach suits your WordPress website will depend on specific requirements. 

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