- Article
- Beginner
- 2 minutes read
- Reviewed August 4, 2026
- WordPress performance
Performance metrics describe different parts of the user and system experience.
No single metric represents every problem. Select measurements according to the layer being investigated.
Server and Network Metrics
Useful measurements include:
- DNS lookup.
- Connection and TLS time.
- Time to First Byte.
- Backend or application time.
- Cache status.
- HTTP status.
- Response size.
A high TTFB can reflect origin processing, cache misses, network distance or queueing.
Visual Loading Metrics
First Contentful Paint measures when the first content is painted.
Largest Contentful Paint measures when the largest visible content element is rendered. It often reflects the combined effect of server response, resource discovery and the loading of a hero image or text block.
Speed Index estimates how quickly visible content fills the viewport in a laboratory test.
Interactivity Metrics
Interaction to Next Paint measures the latency of user interactions across a page visit.
Total Blocking Time is a laboratory metric that reports main-thread blocking between initial paint milestones. It can help diagnose JavaScript work but is not the field replacement for INP.
Visual Stability
Cumulative Layout Shift measures unexpected movement of visible content.
Missing media dimensions, late banners, font changes and inserted content can contribute.
Resource Metrics
Also review:
- Number of requests.
- Transferred and decoded bytes.
- CSS and JavaScript size.
- Main-thread time.
- Long tasks.
- Image payload.
- Third-party requests.
Smaller is not automatically faster, but unnecessary work creates opportunity for delay.
WordPress Application Metrics
Server profiling can include:
- PHP execution time.
- Memory usage.
- Query count and duration.
- Slow functions.
- Remote API calls.
- Cache hit rate.
- Cron backlog.
- Autoloaded option size.
- Admin request time.
Percentiles and Segments
Field metrics should be reviewed by device, geography, connection and page type.
A median can hide poor experiences. Core Web Vitals use the 75th percentile when assessing most visits.
Frequently Asked Questions
Is TTFB a Core Web Vital?
No, but it can strongly influence LCP and overall loading.
Is the Lighthouse performance score a real-user metric?
No. It is a calculated laboratory score from a controlled test.
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