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perf.field-cls-needs-improvement

InfoSEO audit--field-data

On phones, the layout of real visits shifts by more than 0.10 at the 75th percentile: Cumulative Layout Shift (CLS) in the Chrome UX Report's last 28 days, for the page's URL or, when it has too few visits, its origin. Google rates it as needing improvement.

What to change

Give every image width and height, reserve the space of what a script inserts (banners, ads, embeds), and load web fonts with font-display: optional. The Chrome UX Report covers 28 days, so a fix shows there over the next four weeks; check it now with --lighthouse on the local tool, or PageSpeed Insights, which also names the element.

The documentation on developers.google.com

A finding of this rule on a page carries the exact edits for that page: the markup it quotes, and what to write instead.

When it runs

Runs with --field-data (fieldData), on the command and both MCP servers, and in this site's audits: it reads the Chrome UX Report's real-user data. Info is a best practice: worth doing, rarely urgent, and --no-info leaves it out. Each finding takes 1 point off the page's score.

The severity here is the rule's usual one: a finding can be raised or lowered when the page gives a reason.

Run it, or skip it

Check a page for this rule alone, after a fix for instance:

npx @rivi-software/agentic-seo-check audit https://example.com --field-data --rule perf.field-cls-needs-improvement

Or from an assistant, with the MCP tool seo_audit_page:

{
  "url": "https://example.com",
  "fieldData": true,
  "rules": [
    "perf.field-cls-needs-improvement"
  ]
}

To leave it out of an audit, pass --disable perf.field-cls-needs-improvement on the command, or disableRules: ["perf.field-cls-needs-improvement"] to a tool.

All 17 rules