Performance
Core Web Vitals: what they are and why they matter
Google uses Core Web Vitals as a ranking factor. But what do they actually measure?
What are Core Web Vitals?
Core Web Vitals are a set of three metrics that Google uses to assess the user experience of a web page. They measure how fast content loads, how quickly the page becomes interactive and how stable the layout is.
The three metrics
LCP (Largest Contentful Paint)
Measures how fast the largest visible element loads. Target: under 2.5 seconds.
INP (Interaction to Next Paint)
Measures how quickly the page responds to user interactions. Target: under 200 milliseconds.
CLS (Cumulative Layout Shift)
Measures how stable the layout is during loading. Target: under 0.1.
Why they matter
Google uses Core Web Vitals as part of page experience signals for rankings. Fast, stable websites convert better. An improvement of 100ms in LCP leads to 1.1% more conversions. This is an essential part of solid SEO architecture.
Practical improvements
- Optimise images: use WebP/AVIF, set dimensions and lazy-load
- Minimise render-blocking CSS and JavaScript
- Use a CDN for faster content delivery
- Pre-connect to external domains
- Reserve space for ads and embeds
Conclusion
Core Web Vitals aren't an optional extra. They're a fundamental part of a well-performing website. Poor performance can be a sign your website needs a rebuild. Also read how ChatGPT and SEO come together. Get in touch for a performance analysis.