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StackraStackra
Performance

Core Web Vitals Checker

See how fast and stable your pages really feel, on mobile and desktop, with each score explained in plain business terms.

This is one slice of the full scan

A full Stackra scan gives you a Growth Readiness Score, expert AI reviews, a prioritized action plan, and benchmarks you against real businesses in your industry.

How the Core Web Vitals Checker works

Stackra measures three Google signals for the real-world experience of your page: how fast the main content appears (LCP), how stable the layout is while it loads (CLS), and how quickly the page responds to taps and clicks (INP). We report mobile and desktop separately, because most visitors arrive on a phone.

Why do mobile and desktop scores differ?

Phones have slower processors and connections than laptops, so the same page often performs worse on mobile. Since most visitors are on mobile, we show that view first.

Is Time to First Byte part of the score?

No. We show TTFB as helpful background context about your server, but it is a diagnostic value only and does not count toward your Core Web Vitals result.

How do Core Web Vitals affect my business?

Slow or unstable pages make visitors leave before they convert, and they are a ranking factor in Google. Faster, steadier pages keep more people on the page and improve search visibility.

What is a good LCP, CLS, and INP score?

Good field thresholds are LCP at 2.5 seconds or less, CLS at 0.1 or less, and INP at 200 milliseconds or less. LCP measures when the largest content appears, CLS measures unexpected layout movement, and INP measures responsiveness to taps and clicks. Values above these thresholds can make a page feel slow, jumpy, or unresponsive.

Why do so many WordPress sites fail Core Web Vitals?

Plugin bloat is the primary cause. WordPress's flexibility means sites accumulate scripts, stylesheets, and page builders over time, each adding load time. Based on Chrome field data, about 49% of WordPress sites pass all three Core Web Vitals on mobile. Shopify sites pass at around 77%, largely because the platform controls the rendering stack and limits what merchants can add. If you are on WordPress and failing, the fastest wins are usually image optimization, removing unused plugins, and switching to a caching or performance plugin.

Source: HTTP Archive / CrUX Technology Report, August 2026.

What is the fastest thing I can fix?

For most sites, the biggest LCP gains come from image optimization: compressing images, converting to WebP, and adding a width and height attribute so the browser reserves space before the image loads. If your host is slow (high TTFB), upgrading to a CDN-backed host or adding server-side caching is the next lever. Both changes typically cost nothing or very little and show up in field data within two to four weeks.