What is the First Input Delay and How to Fix FID Issues: A Comprehensive Guide

Website performance and user experience play a crucial role in attracting and retaining potential customers. One often overlooked but essential aspect of website performance is First Input Delay (FID). In this comprehensive guide, we will explore what FID is, its importance in website performance and user experience, and practical steps to identify and fix FID issues. By optimizing your website’s First Input Delay, you can improve responsiveness, generate more leads, and stay ahead of your competitors. So, let’s dive in and learn how to enhance your online presence with FID optimization.

Understanding First Input Delay (FID)

First Input Delay (FID) is a crucial web performance metric that measures the time it takes for a website to respond to a user’s initial interaction, such as clicking a button or tapping a link. This metric is essential for understanding and improving website performance and user experience, as it directly affects how users perceive the responsiveness and usability of a site.

Imagine you’re at a coffee shop and you want to order a drink. You approach the counter and eagerly place your order, but the barista seems to be in slow motion, taking their sweet time to respond. It’s frustrating because you want to get your drink and move on with your day. In this scenario, the time between your order and the barista’s response is similar to the First Input Delay (FID) on a web page.

FID is closely related to other web performance metrics, such as Largest Contentful Paint (LCP) and Cumulative Layout Shift (CLS), which together form the Core Web Vitals. These metrics provide a comprehensive view of a website’s overall performance and help identify areas where optimization efforts should be focused. Measuring FID accurately and understanding its implications is essential for optimizing the responsiveness of a website.

First Input Delay (FID) in google pagespeed insights

Measuring First Input Delay

Measuring First Input Delay accurately is crucial for understanding your website’s performance and identifying areas that need improvement. There are several tools available to help you measure FID, such as Google Lighthouse, Google Search Console, and Chrome User Experience Report (CrUX). These tools provide valuable insights into your website’s responsiveness and can help you pinpoint specific issues that may be affecting the user experience.

When using these tools to measure FID, it’s essential to interpret the results effectively. FID results are typically represented in milliseconds (ms), indicating the time it takes for a user’s input to be processed by the browser. Generally, an FID of 100ms or less is considered good, an FID of between 100-300ms needs improvement, and an FID above 300ms is considered poor. Google recommends aiming for an FID of 100ms or less for 75% of your page loads to ensure a satisfactory user experience.

measuring first input delay

Google Lighthouse

To measure the First Input Delay (FID) using Google Lighthouse, follow these steps:

  1. Install and open Google Lighthouse, either as a browser extension or through the Chrome DevTools.
  2. Generate a report by selecting the “Performance” checkbox in Lighthouse and running the audit for your web page.
  3.  Once the audit is complete, view the FID score in the performance report.
  4. The FID score represents the delay users experience when interacting with your web page. A lower score indicates better responsiveness and user experience.

Google Search Console

To measure the First Input Delay (FID) using Google Search Console, follow these steps:

  1. Sign in to your Google Search Console account.
  2. In the left-hand menu, select “Experience” and then click on “Core Web Vitals.”
  3. You’ll see a report that includes various performance metrics, including FID.
  4. Review the FID data to see the distribution of good, needs improvement, and poor URLs in terms of FID.
  5. Use the provided recommendations and insights to optimize your website’s FID and improve the user experience.

Chrome User Experience Report

To measure the First Input Delay (FID) using the Chrome User Experience Report (CrUX), follow these steps:

  1. Access the CrUX database: The CrUX database contains real-world performance data collected from millions of websites. You can access it through the CrUX API.
  2. Query the FID metric: Use the CrUX API to query the FID metric for your website. Specify the desired dimensions such as country, device type, or URL.
  3. Retrieve the FID distribution: Once you’ve executed the query, you’ll receive a distribution of FID values, including percentiles such as 75th or 95th percentile.
  4. Analyze and interpret the data: Review the FID distribution to understand how your website performs in terms of FID compared to other websites.
  5. Take necessary actions: Use the FID data to identify areas of improvement and address any potential performance issues. Optimize your website to reduce FID and enhance the user experience.
Chrome User Experience Report

Common Causes of FID Issues

There are many factors that can affect FID and lead to poor performance. Understanding these causes can help you identify and address them quickly and effectively.

common causes of FID issues
common causes of FID issues

Inefficient JavaScript Execution

One major cause is inefficient JavaScript execution. JavaScript is a powerful programming language used for creating interactive web pages and applications. This can be particularly problematic if JavaScript is executed during the initial loading of the page, as it can block the main thread and prevent the browser from responding to user interactions promptly.

Slow Server Response Times

Another common cause of FID issues is slow server response times. This occurs when the server takes too long to process and respond to requests from users. This can be due to various factors, such as network congestion, server configuration issues, or insufficient server resources.

Resource Contention and Loading Issues

Resource contention and loading issues can also impact FID performance. This occurs when critical resources, such as JavaScript and CSS files, compete for limited browser resources. Inefficient loading of resources, such as loading non-critical files before critical ones, can further exacerbate this problem and contribute to higher FID values.

Strategies for Fixing FID Issues

Once the causes of FID issues have been identified, the next step is to implement strategies to address them. There are several approaches that can be used to improve FID performance, such as breaking up long tasks in JavaScript, using code-splitting and lazy loading techniques, optimizing server response times, and prioritizing resources.

strategies for fixing FID issues
strategies for fixing FID issues

Breaking Up Long Tasks in JavaScript

Breaking up long tasks in JavaScript is an essential strategy for addressing FID issues. Ideally, each task should be completed within 50ms to ensure smooth user experience and prevent browser lock-ups. Popular tools that can aid in breaking up long tasks in JavaScript include Webpack and Gulp.

By splitting lengthy JavaScript tasks into smaller, more manageable pieces, you can prevent the main thread from becoming blocked, allowing user input to be processed more quickly.

Implementing Code-Splitting and Lazy Loading Techniques

Implementing code-splitting and lazy loading techniques can also help reduce FID problems. Code-splitting divides your JavaScript code into smaller chunks, loading only the necessary parts for the current view. Lazy loading, on the other hand, defers the loading of non-critical resources, such as images and videos, until they are needed by the user. This combination of techniques frees up resources and improves overall website performance. 

Optimizing Server Response Times

Optimizing server response times is another crucial step in fixing FID issues. This can be done by optimizing server-side code and ensuring appropriate resources are allocated. This can be achieved by optimizing server-side code, using a content delivery network (CDN), and employing server caching.

Prioritizing Resources

Prioritizing resources, such as CSS and JavaScript files, ensures that critical content is loaded first, reducing the time it takes for a user to interact with your website. This can be done by using techniques like preloading and prioritizing the loading order of your resources.

Using Browser Caching and Prefetching

Lastly, using browser caching and prefetching can further improve FID. Browser caching stores static resources, such as images and stylesheets, in the user’s browser, reducing the need to download them again on subsequent visits. Prefetching, on the other hand, proactively downloads resources that are likely to be needed in the future, improving the overall responsiveness of your website.

Monitoring First Input Delay Improvements

Ongoing performance monitoring is crucial in maintaining optimal website performance and user experience. Regularly assessing First Input Delay using tools like Google Lighthouse and Chrome User Experience Report (CrUX) ensures that any FID issues are quickly identified and addressed. This proactive approach helps prevent potential negative impacts on user experience and lead generation.

Establishing a performance budget is an effective method to manage website performance. A performance budget sets limits on specific metrics, such as FID, and helps guide website development and updates, ensuring that performance remains within acceptable boundaries. This approach encourages developers and content creators to prioritize performance optimization when implementing changes and additions to the website.

The Benefits of Optimizing First Input Delay

The benefits of optimizing First Input Delay are numerous and far-reaching. From improving user experience and website usability to generating more leads and staying ahead of competitors, optimizing FID can have a major impact on the success of any business. Let’s take a closer look at the specific benefits of optimizing First Input Delay.

benefits of optimizing first input delay

Improved User Experience and Website Usability

Optimizing First Input Delay is crucial for several reasons. Firstly, it leads to an improved user experience and website usability. By reducing the time it takes for a website to respond to user interactions, visitors are more likely to stay engaged and explore the site further, ultimately leading to better conversion rates and increased customer satisfaction.

Increased Lead Generation and Customer Acquisition

Secondly, optimizing FID can result in increased lead generation and customer acquisition. When a website is more responsive and provides a seamless experience, users are more likely to complete desired actions such as filling out forms, signing up for newsletters, or making a purchase. This directly translates to a higher return on investment for businesses, as they can capture more leads and convert them into customers.

Enhances Competitiveness in the Digital Landscape

Lastly, optimizing First Input Delay enhances competitiveness in the digital landscape. In today’s fast-paced online environment, a website’s performance can make or break its success. By addressing FID issues and improving website responsiveness, businesses can stay ahead of their competitors and maintain a strong online presence. This not only helps attract new customers but also fosters loyalty among existing clients who appreciate a seamless browsing experience.

Redstitch's Expertise in First Input Delay Optimization

At Redstitch, we pride ourselves on our in-depth knowledge and experience in website optimization, including First Input Delay optimization. Our team of experts uses a data-driven approach to identify and resolve FID issues, ensuring that your website performs at its best and delivers a seamless user experience.

Redstitch’s website optimization services are tailored to your business needs and goals, ensuring that our solutions are both effective and relevant. If your company is interested in learning more about how Redstitch can help you address First Input Delay issues and improve your website performance, don’t hesitate to get in touch with us for a consultation. Our team is always ready to help you take your online presence to the next level.


In today’s digital-focused world, website performance and user experience play a vital role in determining the success of businesses. First Input Delay (FID) is an important metric that directly impacts these two factors. By identifying and addressing FID issues, you can ensure your website is responsive and primed for customer acquisition.

Don’t let poor website performance hold your business back. Let our team at Redstitch help you harness the power of our AI platform and our expertise in website optimization to elevate your online presence and boost lead generation. Reach out to us today for a consultation and take the first step toward unlocking your website’s full potential. Together, we can transform your website into a lead-generating machine and accelerate your business growth.

Picture of Written By: Wes Davis

Written By: Wes Davis

Wes is a seasoned marketing expert with over two decades of experience in the industry. His extensive portfolio includes working with some of the biggest players in the business world as well as small and family-owned business, devising effective marketing strategies to boost growth. He is driven by a passion for helping businesses of all sizes reach their full potential and has a proven track record of delivering measurable results. Outside his professional life, Wes is a devoted family man, a passionate dance dad, and coaches high school baseball. He enjoys traveling and photography as well, capturing moments that matter across the world.

You may also like...