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Web Vitals

Web Vitals are a collection of performance metrics that can be used to measure the performance of a web application. These metrics are collected for each page load and are used to determine the application's overall performance.

Metronome lets you measure the performance of your web application using these metrics.

Web Vitals

Percentiles

Metronome lets you filter how your app is performing for a certain percentage of users. For web vitals, you can select the following percentiles:

PercentileDescription
P50How your app is performing for the 50% of your users (median)
P75How your app is performing for the worst of 25% of your users
P90How your app is performing for the worst of 10% of your users
P95How your app is performing for the worst of 5% of your users
P99How your app is performing for the worst of 1% of your users

Web Vitals Collected

These are the metrics that are collected to be able to calculate your Remix app. (Source: https://web.dev)

Largest Contentful Paint (LCP)

Measures loading performance. To provide a good user experience, LCP should occur within 2.5 seconds of when the page first starts loading.

First Input Delay (FID)

Measures interactivity. To provide a good user experience, pages should have a FID of 100 milliseconds or less.

Cumulative Layout Shift (CLS)

Measures visual stability. To provide a good user experience, pages should maintain a CLS of 0.1. or less.

First Contentful Paint (FCP)

Measures the time from when the page starts loading to when any part of the page's content is rendered on the screen.

Score Calculation

We use the same approach as Lighthouse and Vercel Analytics to get the application score. The score is calculated by a weighted average of the metrics depending on the device.

Score for desktop devices

MetricWeightScore at 50Score at 90
FCP20%4s2.3s
LCP35%4s2.5s
FID30%300ms100ms
CLS15%0.250.10

Score for mobile devices

MetricWeightScore at 50Score at 90
FCP20%1.6s900ms
LCP35%2.4s1.2s
FID30%300ms100ms
CLS15%0.250.10