Sitespeed.io

Performance testing conventionally emphasizes server-side metrics while overlooking browser response variations. Sitespeed.io provides a solution for gathering additional performance intelligence across different hardware, software, and network configurations.

Installation and Execution

Sitespeed.io can be deployed using Docker:

docker run --rm -v "$(pwd)":/sitespeed.io sitespeedio/sitespeed.io:12.1.0 -b chrome --chrome.timeline https://en.wikipedia.org/wiki/Main_Page

You can test multiple URLs in a single run:

docker run --rm -v "$(pwd)":/sitespeed.io sitespeedio/sitespeed.io:12.1.0 -b chrome https://example.com https://example.com/about

Report Analysis

The generated HTML reports include:

• Summary dashboards - Highlighting problem areas at a glance
• Detailed metrics - Covering scores, response times, load times, and resource sizing
• Page-specific comparisons - Useful for identifying performance bottlenecks across multiple URLs

Key Metrics

Sitespeed.io captures important browser-side metrics:

• First Contentful Paint (FCP)
• Largest Contentful Paint (LCP)
• Time to Interactive (TTI)
• Total Blocking Time (TBT)
• Cumulative Layout Shift (CLS)
• Resource load times
• Page weight and asset breakdown

Use Cases

• Comparing performance across different pages
• Monitoring performance over time
• Testing on different browsers and devices
• Identifying frontend bottlenecks
• Validating performance improvements

Conclusion

Sitespeed.io is a valuable addition to performance testing methodologies, particularly for understanding user experience across diverse devices and browsers. It complements rather than replaces comprehensive server-side performance testing frameworks.

Resources

• Official sitespeed.io documentation