Chrome Lighthouse is an open-source, automated website analysis tool developed by Google. It’s built into Chrome DevTools and is used primarily to audit the performance, accessibility, SEO, and other best practices of web pages. Lighthouse is designed to help developers improve the quality of their websites by identifying issues and providing actionable feedback.
What Does Lighthouse Measure?
Lighthouse evaluates a website based on the following key areas:
Performance:
- Measures how quickly your site loads and becomes interactive for users.
- Key metrics include First Contentful Paint (FCP), Speed Index, Largest Contentful Paint (LCP), Time to Interactive (TTI), Total Blocking Time (TBT), and Cumulative Layout Shift (CLS).
Accessibility:
- Evaluates how accessible your site is to users with disabilities.
- Checks for common issues like color contrast, alt text for images, and ARIA attributes.
Best Practices:
- Reviews your site for modern web development best practices.
- Looks at aspects like HTTPS usage, avoiding deprecated APIs, and ensuring the site is mobile-friendly.
SEO:
- Assesses your site’s search engine optimization.
- Evaluates metadata, whether your site is mobile-friendly, and checks for common SEO issues like proper use of meta descriptions and links.
Accuracy and Reliability:
- Accuracy: Lighthouse provides a snapshot of your website’s performance based on a simulated environment. This can differ from real-world user experiences, which are influenced by various factors like network speed, device capabilities, and geographic location. While Lighthouse is highly accurate for identifying potential issues, it’s essential to supplement it with real-world testing.
- Reliability: Lighthouse is considered reliable for detecting issues and providing improvement suggestions. However, since it runs in a controlled environment, the scores can vary depending on factors like the time of day, server load, and the device used for the audit. For consistent results, it’s recommended to run multiple audits and analyze the trends rather than relying on a single score.
Overall, Chrome Lighthouse is a valuable tool for web developers and SEO professionals, offering a comprehensive assessment of a website’s performance and other critical aspects.
Lighthouse’s Achilles Heel: The Challenges of Perfect Scores
Google Lighthouse is an invaluable tool for measuring website performance, but achieving a perfect score can be elusive. Even with meticulous optimization, several factors can significantly impact your Lighthouse results.
Third-party content like Google Maps and analytics tools, while essential, can slow down your site. Similarly, cookie policies and other scripts, though necessary for compliance, can also hinder performance. The weight of JavaScript and CSS frameworks and visually striking elements like full-screen images and videos can further exacerbate load times.
As web developers, we strive to balance functionality with speed. We employ techniques like deferring scripts, minimizing framework usage, and lazy loading to counteract these performance bottlenecks. Additionally, we optimize images using modern formats like WEBP and AVIF to improve load times.
Ultimately, achieving a high Lighthouse score requires a holistic approach that prioritizes both user experience and technical performance.
Run Lighthouse in an Incognito Window?
Running Lighthouse in an Incognito window in Google Chrome is important for several reasons:
- No Browser Extensions Interference: Extensions can affect the performance and behavior of a web page. Incognito mode disables extensions (unless specifically allowed), providing a more accurate analysis of the site’s actual performance.
- No Cache or Stored Data: Incognito mode prevents cached data, cookies, or stored session information from impacting the results, ensuring that the analysis reflects a first-time visitor’s experience.
- Isolated Environment: Running the tool in an Incognito window isolates the test from any background processes or logged-in sessions, reducing the chances of external factors skewing the results.
By running Lighthouse in Incognito mode, you get a more controlled and realistic assessment of the website’s performance and user experience.