PageSpeed Insights (PSI) analyses a page's user experience on mobile and desktop devices and makes recommendations for how to enhance it.
PSI offers a page's lab and field data. Because it is obtained in a controlled environment, lab data is important for troubleshooting. However, it is possible that it will not capture real-world bottlenecks. Field data is useful for collecting authentic, real-world user experience, but it provides fewer metrics.
Performance Audits
These checks ensure that your page is optimized for users to be able to see and interact with page content.
A) Performance audit scoring
1. Lighthouse performance scoring
B) Metrics
1. First Contentful Paint
2. Speed Index
3. Total Blocking Time
4. Largest Contentful Paint
5. Cumulative Layout Shift
C) Opportunities
1. Eliminate render-blocking resources
2. Properly size images
3. Defer offscreen images
4. Minify CSS
5. Minify JavaScript
6. Remove unused CSS
7. Efficiently encode images
8. Serve images in modern formats
9. Enable text compression
10. Preconnect to required origins
11. Reduce server response times
12. Avoid multiple page redirects
13. Preload key requests
14. Use video formats for animated content
15. Reduce the impact of third-party code
16. Avoid non-composited animations
17. Lazy load third-party resources with facades
D) Diagnostics
1. Avoid enormous network payloads
2. Serve static assets with an efficient cache policy
3. Avoid an excessive DOM size
4. Avoid chaining critical requests
5. User Timing marks and measures
6. Reduce JavaScript execution time
7. Minimize main thread work
8. Ensure text remains visible during webfont load
9. Keep request counts low and transfer sizes small
10. Ensure the page can be restored from the back/forward cache
E) Retired metrics
1. Time to Interactive
2. First Meaningful Paint
3. First CPU Idle
4. Max Potential First Input Delay
