Performance
Core Web Vitals, properly
Why are real users getting a slow page, and what fixes it?
Field data first, then the lab: LCP by sub-part, INP by phase and long animation frames, CLS by cause, and third-party tags. Verifies the lab run and the served markup, and is honest that field data takes weeks to move.
Paste into Claude Code, Cursor, Codex or any agent that can open a link. If yours cannot, use Copy full text.
Reach for it when you say
- “Core Web Vitals failing”
- “Poor LCP”
- “INP too high”
- “Third-party tags slowing the site”
Installed as a skill, it triggers on requests like these by itself.
- Step 01Read the field data first: what real users get
- Step 02Reproduce it in the lab and find the cause per metric
- Step 03Fix LCP by sub-part, INP by phase and CLS by cause
- Step 04Verify the lab run and served markup, then re-check the field later
Three modes, three ways in
Run it in audit mode first: it records findings and changes nothing. Then fix applies only the findings you approve, and re-check re-tests them later. Switch modes on the prompt above.
- 01Paste the link promptOne line that points your agent at the skill on GitHub. Nothing to install, always the latest version.
- 02Paste the full textFor agents that cannot open links. The skill is self-contained, so this works in any chat.
- 03Install the packInstalled as skills, it triggers by itself when you describe the problem, and can hand work to the other skills.
Questions about this skill?
Ask me on LinkedIn, or open an issue on GitHub if something is wrong or missing.