Optimizing Website Performance: A Comprehensive Google Lighthouse Study on Desktop and Mobile Modes
Ahmed Sameer AL-Majidi · 2025
The performance of websites is a major factor for user satisfaction and experience, especially in areas where the internet is slow or the operating device has limited capabilities. Therefore, Google developed the Lighthouse tool to evaluate and improve website performance and quality. This tool is open-source used to measure Performance, Accessibility, SEO, Best Practices and PWA. However, the consistency and reliability of its results, particularly via the Command Line Interface (CLI), have not been thoroughly explored. Therefore, this study aimed to investigate the reliability and consistency of Lighthouse results. Lighthouse was run on a real website using both CLI and Chrome DevTools under desktop and mobile modes multiples times. Additional tests on two well-known sites: Wikipedia and The New York Times were run using DevTools. Each audit category score was recorded, Performance scores significantly fluctuated: CLI runs ranged 86-95, and DevTools tests revealed values 21-100 across various devices and sites, while Accessibility, SEO, and Best Practices scores remained consistent (mostly above 90). It was hypothesized that Performance scores varied significantly depending on the mode (Desktop and Mobile) and website complexity, while other categories stayed mostly stable. These findings suggest that developers may need to repeat tests for more stable outputs. This paper highlights both the features and limitations of Lighthouse as an auditing tool, and offers insights into best-use practices for web developers and researchers.