Ideas for Detecting Web Vitals Problems

web-vitals-suggestions.md

Idea	How We'd Detect It
Notify users when image not served from cache / CDN.	Header attributes on image asset spans.
Suggest file formats such as WebP or AVIF.	Image asset span has an extension like .bmp.
Notify of render blocking assets during pageload.	Look at structure of resource.script spans.
Notify when page has >800 DOM elements.	On bad INP count DOM nodes.
Warn on long animation frames correlated to INP.	Long animation frame API
Slow database calls that correlate to a bad TTFB.	Correlate TTFB to a corresponding DB call
Slow backend route calls that correspond a bad TTFB.	Correlate http.server spans to bad TTFB.
Warn about images missing dimensions.	When a bad CLS occurs, collect images without dimension attributes on page.
Warn if web fonts are slow to load (contributing to CLS).	Resource timing API.
Detect whether slow LCP is caused by a slow API call.	Detect when an http.client span completes immediately before an LCP node.