Audit Your Website Performance with Google Lighthouse

Audit your website’s speed, SEO, and user experience using Google Lighthouse. Learn step-by-step optimization strategies for peak performance!

What is Google Lighthouse?

Google Lighthouse is designed to evaluate various aspects of web pages, including performance, accessibility, best practices, and SEO. By running a Lighthouse audit, you receive a comprehensive report highlighting areas that need improvement, along with actionable suggestions.

Accessing Google Lighthouse via Chrome DevTools

Google Lighthouse is integrated into Chrome DevTools, making it convenient to audit web pages directly from your browser. Follow these steps to conduct an audit:

1. Open Chrome DevTools

• Launch an Incognito Window:
  • Click the three dots in Chrome’s upper-right corner and select New incognito window.
  • Shortcut:
    • Windows/Linux: Ctrl + Shift + N
    • Mac: Cmd + Shift + N
• Navigate to the Webpage: Enter the URL of the page you wish to audit.
• Open DevTools:
  • Right-click anywhere on the page and select Inspect.
  • Shortcut:
    • Windows/Linux: Ctrl + Shift + I
    • Mac: Cmd + Option + I

2. Navigate to the Lighthouse Panel

• Click the double arrow icon (>>) in DevTools to access hidden panels.
• Select Lighthouse from the dropdown menu.

3. Configure the Audit

• Choose the Mode:
  • Navigation: Analyzes the page as it loads from scratch (like when a user first visits the site).
  • Timespan: Tracks performance and interactions over a period of time (e.g., while a user scrolls or clicks around).
  • Snapshot: Analyzes the webpage exactly as it appears when you run the audit. It doesn’t simulate a page load or track interactions over time—it just looks at the page as it is right now.
    • Great for checking Image Sizes: If you’ve uploaded images to your website, you might want to ensure they’re not too large or too small for their containers. Snapshot mode can help you identify if images are properly optimized.
• Select the Device Type:
  • Mobile: Simulates a mobile browsing experience.
    • Google primarily uses the mobile version of websites for indexing and ranking, a practice known as mobile-first indexing.
  • Desktop: Simulates a desktop browsing experience.
  • Why Compare?
    • Performance Metrics: Performance can vary significantly between devices. Mobile devices may have different processing capabilities and network conditions compared to desktops. Testing helps in optimizing load times and responsiveness for all users.
    • Responsive Design Validation: Even with responsive design techniques, elements may not always adapt perfectly to different screen sizes. Testing allows you to verify that layouts, images, and text scale appropriately on various devices.
• Select Categories to Audit:
  • Performance – Checks how fast your website loads and responds. A slow website can frustrate visitors and make them leave before the page even loads.
  • Accessibility – Looks for problems that might make it hard for people with disabilities (like those using screen readers or keyboard navigation) to use your site.
  • Best Practices – Makes sure your website follows modern web design rules, like keeping it secure, mobile-friendly, and free from coding errors.
  • SEO (Search Engine Optimization) – Helps your website show up better in Google searches by checking things like page structure, keywords, and mobile friendliness.

4. Run the Audit

• Click Analyze page load to initiate the audit.
• Lighthouse will generate a detailed performance report with scores and actionable insights.

Why Run Lighthouse Audits in Incognito Mode?

Conducting audits in Incognito Mode ensures more accurate performance results by eliminating potential interferences.

1. Avoid Browser Extensions Interference

• Extensions can inject scripts and styles that affect audit outcomes.
• Incognito Mode disables extensions, providing a clean testing environment.

2. Prevent Cached Data from Skewing Results

• Cached resources can improve load times for repeat visitors, leading to inflated performance scores.
• Incognito Mode forces a fresh page load, mimicking a first-time visitor’s experience.

3. Exclude User-Specific Data

• Personalized settings, login states, and dynamic content can alter audit outcomes.
• Incognito Mode presents a neutral user experience, reflecting what most visitors encounter.

Interpreting Lighthouse Audit Results

Lighthouse provides scores across four categories: Performance, Accessibility, Best Practices, and SEO. Here’s how to interpret and act on these results:

1. Performance Metrics

Lighthouse measures key performance indicators, including:

• First Contentful Paint (FCP): Time until the first visible content appears.
• Largest Contentful Paint (LCP): Time until the largest visible element is rendered.
• Time to Interactive (TTI): Duration until the page becomes fully interactive.
• Total Blocking Time (TBT): Measures input delay due to heavy JavaScript execution.
• Cumulative Layout Shift (CLS): Detects unexpected page shifts affecting user experience.

Optimization Tips:

• Compress Images – Use newer image formats like WebP or AVIF to make image files smaller without losing quality. This helps pages load faster. Free tools like TinyPNG and Squoosh allow you to quickly optimize images without noticeable loss in quality.
• Minify CSS, JavaScript, and HTML – Remove unnecessary spaces and code from your website files to make them load quicker.
• Leverage Browser Caching – Tell browsers to save certain files (like images and scripts) so they don’t have to be downloaded again every time someone visits your site.
  • How to Set Browser Caching in WordPress
    • Use a Plugin (Easy & Recommended)
    • W3 Total Cache (Free)
      • Steps to enable caching using W3 Total Cache:
      • Install & activate W3 Total Cache from the WordPress Plugin Directory.
      • Go to Performance → Browser Cache in the WordPress dashboard.
      • Enable the following options:
        • Set expires header
        • Set cache control header
        • Enable HTTP (gzip) compression
        • Disable cache for logged-in users (optional)
      • Click Save Settings & Purge Caches.
• Eliminate Render-Blocking Resources – Load the most important parts of your website first (like styles and layout) and delay less essential scripts so the page appears faster. Free tools like Autoptimize (for WordPress) can help remove render-blocking issues.

2. Accessibility

Lighthouse audits for accessibility issues, such as:

• Missing alt text for images
• Low color contrast affecting readability
• ✅ Optimization Tips:
• Add Alt Text to Images – Write short descriptions for images so screen readers can describe them to visually impaired users.
• Use High-Contrast Colors – Make text easy to read by ensuring enough contrast between text and background colors.
• Organize Content Clearly – Use proper headings, bullet points, and sections so people can easily navigate the page.

3. Best Practices

Lighthouse evaluates modern web development standards, including:

• Use HTTPS – Protect user data by making sure your website has a secure SSL certificate.
• Avoid Outdated Code – Don’t use old or deprecated APIs that may have security risks or stop working in the future.
• Secure External Requests – When your site connects to other websites (APIs, images, or scripts), ensure they are trusted and secure to prevent security threats.

4. SEO (Search Engine Optimization)

Lighthouse assesses key technical SEO factors that impact search rankings:

• Meta descriptions: Are they concise and keyword-rich?
• Structured data: Are schema markups implemented?
• Mobile-friendliness: Is the page responsive and touch-friendly?

✅ Optimization Tips:

• Write Clear & Engaging Meta Descriptions – A meta description is the short text that appears under your page title in search results. Make it compelling so people want to click your link.
• Use Structured Data for Better Search Results – Structured data helps Google understand your content and display rich results (like star ratings, FAQs, and product details). You can check if your structured data is correct using:
  • Schema Markup Validator – Helps verify if your structured data is properly formatted.
  • Google’s Rich Results Test – Tests if your page qualifies for rich snippets in search results.
• Make Sure Your Site is Mobile-Friendly – Many people browse on their phones, so check that:
  • Tap targets (buttons and links) are large enough to click easily.
  • Text is easy to read without zooming in.

Reviewing Lighthouse Recommendations

To further fine-tune website performance, expand Lighthouse Diagnostics to identify:

• Render-blocking resources: Defer non-critical JavaScript and CSS
• Unoptimized images: Compress and serve in WebP format
• Excessive JavaScript execution time: Minimize unused JavaScript
• Learn more about the Lighthouse results.

Beyond Lighthouse: Additional Tools for Optimization

Lighthouse is just one piece of the puzzle. To fully optimize your website, leverage additional tools for deeper insights.

Performance Monitoring Tools

• Google PageSpeed Insights (this is Lighthouse performance mode but in a browser form)
• GTmetrix
• WebPageTest

SEO Tools

• Google Search Console
• Ahrefs Site Audit

Conclusion

Google Lighthouse is a powerful tool for optimizing website speed, accessibility, best practices, and SEO. Regular audits will help you maintain peak performance, enhance search rankings, and improve the user experience.

🔹 Next Steps:

• Run Lighthouse audits regularly to monitor improvements
• Address flagged issues to enhance website speed and usability
• Use additional SEO and performance tools like Google Search Console & GTmetrix

🚀 Start using Google Lighthouse today to improve your site’s speed, usability, and search rankings! 🚀

This article is for informational and entertainment purposes only and does not constitute professional advice. Please consult a qualified professional for your specific needs. Swirly Sky Ventures LLC assumes no responsibility or liability for any actions taken based on the information provided in this article. For more details, please review our Terms of Use.

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