How to Use PageSpeed Lighthouse to Improve Website Performance

Website performance is crucial for user experience and SEO rankings. Slow-loading pages can frustrate users, increase bounce rates, and affect conversions. One of the best tools to measure and improve website performance is PageSpeed Lighthouse. This tool provides valuable insights into how your website performs and gives recommendations to enhance its speed. In this article, we will explain what PageSpeed Lighthouse is and how to use it to improve your website performance.

What is PageSpeed Lighthouse?

PageSpeed Lighthouse is an open-source, automated tool created by Google. It helps web developers, designers, and website owners measure the performance of their web pages. Lighthouse runs audits on your website, analyzing aspects such as performance, accessibility, SEO, and more.

The tool generates a report with a score ranging from 0 to 100 for different metrics, such as First Contentful Paint (FCP), Largest Contentful Paint (LCP), Cumulative Layout Shift (CLS), and others. These metrics are part of the Core Web Vitals that Google uses to evaluate user experience and rank websites.

Why Use PageSpeed Lighthouse?

Using PageSpeed Lighthouse helps you identify issues that affect your website’s speed and performance. Some of the key reasons to use it include:

1. Improves User Experience: Faster websites result in better user engagement and satisfaction.
2. Boosts SEO Rankings: Google considers website performance as a ranking factor. A well-optimized website can rank higher.
3. Provides Actionable Insights: Lighthouse gives clear suggestions on how to fix performance issues.
4. Monitors Core Web Vitals: It helps you measure important metrics like LCP, FCP, and CLS, which Google uses for ranking.

How to Use PageSpeed Lighthouse

Using PageSpeed Lighthouse is straightforward. You can run the tool in several ways, including using Google Chrome DevTools, as a standalone Chrome extension, or through the command line. Below are the steps for using it in different methods.

Method 1: Using Chrome DevTools

1. Open Google Chrome: Launch Chrome and navigate to the website you want to test.
2. Open DevTools: Press F12 or Right-click on the page and select Inspect to open DevTools.
3. Navigate to the Lighthouse Tab: In the DevTools panel, click on the Lighthouse tab.
4. Select Audit Options: You can choose what kind of audit you want to run. Select options for Performance, Accessibility, Best Practices, SEO, and PWA (Progressive Web App).
5. Click Generate Report: After selecting your options, click the Generate Report button. Lighthouse will then run the audit.
6. Review the Report: Once the report is generated, you will see the performance score along with suggestions for improvements.

Method 2: Using the PageSpeed Insights Website

1. Visit PageSpeed Insights: Go to the PageSpeed Insights website (https://developers.google.com/speed/pagespeed/insights/).
2. Enter Your Website URL: Enter the URL of the website you want to test.
3. Click Analyze: Click on the Analyze button to run the test.
4. View the Report: The PageSpeed Insights tool will provide a report, including the Lighthouse performance score and suggestions for improvement.

Method 3: Using the Lighthouse Chrome Extension

1. Install the Extension: Go to the Chrome Web Store and search for the Lighthouse Chrome Extension. Click Add to Chrome to install it.
2. Navigate to Your Website: Once the extension is installed, go to the website you want to test.
3. Launch Lighthouse: Click on the Lighthouse icon in your browser’s toolbar. This will open the extension.
4. Select Audit Options: Choose the categories you want to test, such as Performance, SEO, and Accessibility.
5. Generate the Report: Click the Generate Report button. Lighthouse will run the audit and display the results.

Method 4: Using the Command Line

1. Install Node.js: To use Lighthouse from the command line, first install Node.js on your computer.
2. Install Lighthouse: After installing Node.js, use the command npm install -g lighthouse to install Lighthouse globally.
3. Run Lighthouse Audit: Open the command line and type the following command:
   lighthouse <URL> --view
   Replace <URL> with the website URL you want to audit. This command will run Lighthouse and open the report in your default browser.

Key Metrics to Focus on in PageSpeed Lighthouse

When using PageSpeed Lighthouse, several key metrics are essential to improving website performance. These metrics are part of the Core Web Vitals, which Google uses to assess user experience.

1. First Contentful Paint (FCP)

FCP measures the time it takes for the first piece of content to appear on the screen after the page starts loading. A fast FCP improves the perceived speed of your website.

• Best Score: 1.8 seconds or less.
• Actionable Tip: Optimize server response time and minimize blocking resources to improve FCP.

2. Largest Contentful Paint (LCP)

LCP measures how long it takes for the largest visible content element (e.g., an image or video) to load. A slow LCP can lead to a poor user experience.

• Best Score: 2.5 seconds or less.
• Actionable Tip: Optimize images and implement lazy loading for better LCP.

3. Cumulative Layout Shift (CLS)

CLS measures how much the layout shifts as the page loads. A high CLS score can make the page feel unstable and frustrating to use.

• Best Score: 0.1 or less.
• Actionable Tip: Set the size for images and fonts, and avoid content shifts by using stable containers.

4. Total Blocking Time (TBT)

TBT measures the total time the page is blocked from responding to user input. Reducing TBT improves the interactivity of your website.

• Best Score: 200 ms or less.
• Actionable Tip: Optimize JavaScript and remove render-blocking resources to reduce TBT.

5. Speed Index

Speed Index measures how quickly the contents of a page are visually populated. The lower the Speed Index, the faster your page appears to load.

• Best Score: Below 3,000.
• Actionable Tip: Optimize the rendering path and eliminate unnecessary animations or effects.

Tips for Improving Website Performance Based on Lighthouse Reports

After running the PageSpeed Lighthouse audit, you will get a report with specific suggestions for improving website performance. Here are some common recommendations and how to address them:

1. Optimize Images

Large images can slow down your website. Use image compression tools and serve images in modern formats like WebP for better performance.

2. Minimize JavaScript and CSS

Remove unused JavaScript and CSS. Use code-splitting to load only the necessary parts of your site.

3. Enable Caching

Implement caching to store static resources, reducing the need to fetch them repeatedly.

4. Use a Content Delivery Network (CDN)

A CDN distributes content across multiple servers, reducing load times for users by serving content from the nearest server.

5. Reduce Server Response Time

A slow server can delay the loading of your website. Use faster hosting solutions or optimize your server configuration.

Conclusion

PageSpeed Lighthouse is an excellent tool for web developers and website owners who want to improve website performance. By using Lighthouse to identify performance bottlenecks, you can make improvements that enhance user experience, increase SEO rankings, and reduce bounce rates. Regularly running audits and addressing the issues highlighted in the reports will keep your website fast, responsive, and user-friendly. By following the best practices and focusing on Core Web Vitals, you can optimize your website for better performance in 2025.

FAQs

Q1: How often should I run a Lighthouse audit?
Run a Lighthouse audit regularly, especially after major updates or changes to your website.

Q2: What is the ideal PageSpeed score?
Aim for a score of 90 or above. Scores between 50 and 90 are acceptable, but improvements are needed.

Q3: Can PageSpeed Lighthouse affect my website’s SEO ranking?
Yes, Google uses Lighthouse’s performance metrics as part of its ranking algorithm. A better Lighthouse score can improve SEO.

Q4: Is PageSpeed Insights the same as Lighthouse?
Yes, PageSpeed Insights uses Lighthouse in the background to provide detailed performance reports for websites.

Q5: What’s the most important Lighthouse metric for improving user experience?
The LCP (Largest Contentful Paint) is crucial for user experience. It measures when the main content of your page becomes visible.