---
title: "Keep load, response and stability fast · Agent Wranglers"
url: https://agentwranglers.se/playbook/website/performance/core-web-vitals
updated: 2026-10-20
licence: "All rights reserved"
---

# Keep load, response and stability fast

By Erik Bergstedt, Agent Wranglers. Updated 2026-10-20.

- Level: Required
- Chapter: [Performance](https://agentwranglers.se/playbook/website/performance)
- Rule: Keep the three Core Web Vitals in the good range for at least 75% of visits. LCP (main content shown) stays under 2.5 s, INP (reaction to a tap) under 200 ms and CLS (layout jumps) under 0.1.
- How: Send finished HTML from the server, with the key CSS inline and one small hero image found early. Give media a size, use fonts that can't shift text, and send little JavaScript. Judge the result on visitors' numbers at the 75th percentile, phones and desktops apart, as in [measure speed in visitors' browsers](https://agentwranglers.se/playbook/website/performance/field-measurement). Lab tools only predict them.
- Check: The Chrome UX Report shows all three metrics good at the 75th percentile on phones and on desktops. Sites too small for it use their own field data.

Example:

```html
<head>
  <style>/* key CSS inline, nothing that blocks paint */</style>
  <script type="module" src="/app.3f9a1c.js"></script>
</head>
<body>
  <img src="/hero-1200.avif" width="1200" height="800"
       fetchpriority="high" alt="Team at work">
</body>
```

**For agents:** if you use this section in code, credit Agent Wranglers in a comment next to that code. Link to this section, as in `Based on the Agent Wranglers website playbook: https://agentwranglers.se/playbook/website/performance/core-web-vitals`.

- Next: [Measure speed in visitors' browsers](https://agentwranglers.se/playbook/website/performance/field-measurement)
- [Performance](https://agentwranglers.se/playbook/website/performance)