# How fast is your site, really?

Monitor Core Web Vitals from real users, not synthetic tests. LCP, FID/INP, and CLS with percentile analysis, device breakdowns, and geographic maps.

## Web Vitals

| Metric                          | P50      | P75 | P90 | P99 | 
|---------------------------------|----------|-----|-----|-----| 
| Largest Contentful Paint        | 00ms     |     |     |     | 
| Cumulative Layout Shift         | 00      |     |     |     | 
| Interaction to Next Paint      | 00ms     |     |     |     | 
| First Contentful Paint          | 00ms     |     |     |     | 
| Time to First Byte              | 00ms     |     |     |     |

No performance data available. Try adjusting your date range or filters.

## What you can do

### Core Web Vitals

Monitor LCP (Largest Contentful Paint), FID/INP (Interaction to Next Paint), and CLS (Cumulative Layout Shift), the metrics Google uses for search ranking.

### Percentile analysis

View performance at the P75, P90, and P99 levels. Averages hide the slow tail; percentiles show how your slowest users actually experience your site.

### Device & browser breakdown

See performance by device type, browser, and operating system. Identify if mobile Safari users have worse LCP than desktop Chrome users.

### Geographic performance map

Visualize performance by region on an interactive map. Spot countries or regions where your site is slow due to CDN gaps or server distance.

### Time-series trends

Track how your Web Vitals change over time. Correlate performance regressions with deployments or traffic spikes.

### Real user monitoring

All metrics come from real users, not synthetic tests. See actual performance as your visitors experience it.

## How it works

1. **Enable Web Vitals tracking**: Add `trackWebVitals: true` to your Rybbit configuration. The tracking code uses the standard web-vitals library to measure CWV metrics.
2. **Real user data is collected**: As visitors browse your site, their actual LCP, FID/INP, and CLS values are measured and sent to Rybbit. No synthetic tests, just real performance from real users.
3. **View the Performance dashboard**: Navigate to Performance in your dashboard. See overview cards, time-series charts, dimension breakdowns, and the geographic performance map.
4. **Identify and fix issues**: Spot which devices, browsers, or regions have poor performance. Use the data to prioritize optimization efforts where they matter most.

## Who uses this

### Developers & engineers

Monitor performance regressions in production. Correlate deploy times with CWV changes to catch issues before they affect SEO.

### SEO teams

Core Web Vitals directly impact search rankings. Track real-user metrics to ensure your site meets Google's performance thresholds.

### UX & design teams

Ensure your designs perform well in production. CLS monitoring catches layout shifts that create jarring user experiences.

### Platform teams

Set performance budgets and monitor them continuously. Get real user data across all device types and geographies.

### Agency developers

Monitor performance across client sites. Show clients real data on how their site performs for actual visitors.

### E-commerce teams

Page speed directly impacts conversion rates. Monitor LCP to ensure your product pages load fast enough to keep shoppers engaged.

## Frequently asked questions

### What are Core Web Vitals?

### How does this differ from Lighthouse or PageSpeed Insights?

### Does tracking Web Vitals add overhead to my site?

### What percentiles are available?

### Can I see performance by page?

### Is this available on all plans?