Performance Required

Keep load, response and stability fast

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.

By Erik Bergstedt, Agent Wranglers. Updated 20 October 2026.

How to do it

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. Then measure visitors (Chrome UX Report) as well as the lab.

Example

<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>

How to check

Lighthouse and the Chrome UX Report show good values for LCP, INP and CLS.

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.