Web vitals represent elements of the user experience in a session that can be measured, quantified, and rated on a three point scale: Good, Improvable, or Poor.
Noibu tracks the three Core Web Vitals, as well as additional web metrics. These metrics are tracked individually with each Session recording, and also summarized in aggregate in the Web Performance Dashboard.
Core Web Vitals
| Core Web Vital | Description | Benchmarks |
| Largest Contentful Paint (LCP) | The time to render the largest content element (usually an image or video). Usually, a poor LCP score is caused by oversized files, uncompressed images, JavaScript and CSS that blocks rendering, or slow server response time. |
Good: ≤ 2.5s Improvable: ≤ 4s Poor: > 4s |
| Interaction to Next Paint (INP) | The time to respond to user interactions (mouse clicks, taps, and keystrokes). A faster INP indicates a more responsive page and ensures a smooth user experience. A poor INP score indicates the page may appear laggy to users. |
Good: ≤ 200ms Improvable: ≤ 500ms Poor: > 500ms |
| Cumulative Layout Shift (CLS) | Instances of layout shift, where a page element changes position or size. This causes content on the page to shift and creates a poor user experience. Often, a poor CLS score is due to ads, dynamically injected content, and embeds and iframes without dimensions. |
Good: ≤ 0.1 Improvable: ≤ 0.25 Poor: > 0.25 |
Note: though Noibu collects web vital information from each session, technical limitations in certain browsers prevent the measurement of certain vitals. The following table outlines which web vitals can and cannot be tracked by browser.
| Web Vital |
Chromium (includes Chrome and Edge) |
Firefox | Safari |
| LCP | Supported | Supported | Unsupported |
| INP | Supported | Unsupported | Unsupported |
| CLS | Supported | Unsupported | Unsupported |
Additional Web Metrics
| First Contentful Paint (FCP) | The time for the browser to render the first content–text or image–after a user clicks a URL. This quantifies response times, and the longer it takes the render the first piece of content, the lower the user experience. |
Good: ≤ 1.8s Improvable: ≤ 3s Poor: > 3s |
| Time to First Byte (TTFB) | Measures the time between the request for a resource and when the first byte of a response begins to arrive. This accommodates redirect time, service worker startup time, DNS lookup, connection and TLS negotiation, and the request itself. A longer connection setup time contributes to a poor user experience. |
Good: ≤ 800ms Improvable: ≤ 1800ms Poor: > 1800ms |
| First Input Delay (FID) | Measures the time between when a user interacts with a page and when the browser responds to the interaction. This could be how long after a user clicks a link or taps a button that the browser begins the action. Delays of this sort indicate slow loading times. Often, a slow FID is caused by bloated JavaScript files. |
Good: ≤ 100ms Improvable: ≤ 300ms Poor: > 300ms |
Web Vitals in Sessions
With the help of web vitals, you can use the Sessions table to investigate poor performing pages and implement improvements to the user experience. For example, if you filter the sessions list by a product URL and apply a poor web vital score, you can find sessions where users have visited that page and encountered poor performance.
Learn more about filtering session recordings.
Web Vitals in Web Performance Dashboard
You can see an aggregate measure of web vitals from all user sessions in the Web Performance Dashboard. This presents core web vitals summarized for your entire website.
Optimizing web vitals has a greater impact than improving the user experience. In eCommerce, every extra second of loading time creates drop-off, so merchants should monitor web vitals and optimize performance to ensure a healthy funnel.
Additionally, good web vitals can increase traffic to an eCommerce site by improving SEO. Because Google prioritizes pages with fast loading times, pages with poor web vitals will tend to rank lower in Google search results.