Core Web Vitals
Measure real-world page performance via Google PageSpeed Insights — LCP, INP, CLS, and more with historical tracking.
Core Web Vitals lets you measure real-world performance for any crawled page using the Google PageSpeed Insights API v5. Get Lighthouse scores, detailed metric breakdowns, and historical trends for both mobile and desktop — all from within SerpWise.
Overview
SerpWise integrates with the PageSpeed Insights API to provide on-demand performance measurements. Each measurement runs a full Lighthouse analysis and returns:
- Core Web Vitals metrics (LCP, INP, CLS)
- Additional performance metrics (FCP, TTFB, SI, TBT)
- A composite performance score (0–100)
- Optimization opportunities and diagnostics
- Both mobile and desktop results
Historical measurements are stored so you can track performance trends over time.
Metrics
Each measurement captures the following metrics with Good / Needs Improvement / Poor thresholds:
| Metric | Good | Needs Improvement | Poor | Description |
|---|---|---|---|---|
| LCP (Largest Contentful Paint) | ≤ 2.5s | ≤ 4.0s | > 4.0s | Time until the largest visible element renders |
| INP (Interaction to Next Paint) | ≤ 200ms | ≤ 500ms | > 500ms | Responsiveness to user interactions |
| CLS (Cumulative Layout Shift) | ≤ 0.1 | ≤ 0.25 | > 0.25 | Visual stability — how much the layout shifts |
| FCP (First Contentful Paint) | ≤ 1.8s | ≤ 3.0s | > 3.0s | Time until the first content renders |
| TTFB (Time to First Byte) | ≤ 0.8s | ≤ 1.8s | > 1.8s | Server response time |
| SI (Speed Index) | ≤ 3.4s | ≤ 5.8s | > 5.8s | How quickly content is visually populated |
| TBT (Total Blocking Time) | ≤ 200ms | ≤ 600ms | > 600ms | Total time the main thread was blocked |
Each metric is color-coded: green (good), amber (needs improvement), or red (poor).
Measuring a Page
- Navigate to any URL Detail page
- Click the Performance tab
- Click Measure to run a PageSpeed Insights analysis
The measurement takes a few seconds to complete. Results appear for both mobile and desktop once the analysis finishes.
Credit Usage: Each performance measurement costs 1 credit. Measurements are not automatic — you choose which pages to measure and when.
Historical Trends
Every measurement is stored, building a history of performance data for each URL. The Performance tab shows:
- Line charts for each metric over time
- Mobile vs. desktop comparison on the same chart
- Trend indicators showing whether performance is improving or regressing
Use historical data to verify that optimizations (caching changes, image optimization, code splitting) are having the desired effect.
Lighthouse Opportunities
Below the metrics, the Performance tab displays Lighthouse optimization opportunities — specific suggestions for improving performance, such as:
- Properly size images
- Eliminate render-blocking resources
- Reduce unused JavaScript
- Serve images in next-gen formats
- Enable text compression
Each opportunity includes an estimated time savings and a priority level.
Performance Grading
Pages receive a performance grade based on the composite Lighthouse score:
| Score | Grade |
|---|---|
| 90–100 | A |
| 80–89 | B |
| 70–79 | C |
| 60–69 | D |
| 0–59 | F |
Domain Performance Summary
From the domain dashboard, you can see aggregate performance data across all pages that have been measured. This includes:
- Average performance score across measured pages
- Distribution of performance grades
- Pages with the worst performance scores for prioritized optimization