First Input Delay (FID)

It measures the time it takes for a user to interact with a page after it has loaded

Stiven Castillo
June 07, 2023

First Input Delay (FID) is a web performance metric that measures the time it takes for a user to interact with a page after it has loaded. This could be clicking a button, typing in a text field, or scrolling the page.

FID is important because it is a measure of how quickly a user can start interacting with a page. A long FID means that the user will have to wait longer before they can start using the page, which can lead to a poor user experience.

There are a number of things that can affect FID, including:

  • The size and complexity of the page
  • The use of images and other large resources
  • The loading speed of the server
  • The performance of the user’s device

There are a number of things you can do to improve FID, including:

  • Minifying and compressing your CSS and JavaScript files
  • Using lazy loading for images and other large resources
  • Serving your pages from a CDN
  • Optimizing your JavaScript code
  • Using a Content Delivery Network (CDN)

FID is one of the Core Web Vitals metrics, which are a set of performance metrics that Google uses to measure the quality of a web page. A good FID score is considered to be under 100 milliseconds.