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Core Web Vitals


First Input Delay (FID) Explained

Learn How to Improve First Input Delay (FID) Scores for Your Website

Rick Bucich
First Input Delay (FID)

First Input Delay (FID) is a performance indicator that measures the time between a user’s input and the screen responding to that input.

It’s also known as First Input Latency. While it might sound like an obscure technical measurement, FID is an important indicator of how responsive and helpful your web pages will be for users.

With the rise of mobile device usage and the need for fast-loading websites, performance indicators like FID have become increasingly important. Although FID is no longer a core web vital metric, optimizing for fast response times remains crucial.

This blog post will give you everything you need to know about FID, what it means for your web pages, and how you can optimize your web pages for fast response times.

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What Is First Input Delay (FID)?

First input delay, or first input latency, refers to when a user takes action and when that action is reflected on the screen.

"First Input" refers to the first user input action, such as clicking a button or tapping on a link, after a web page starts loading. FID measures the delay or time gap between when the user interacts with the web page for the first time and when the web page responds.

A higher first input delay can have a big impact on usability because it can make users feel like the website is unresponsive.

First Input Delay is the time between the user’s first tap and when the web page responds to that tap. If a user taps the web page and waits 2 seconds for something to happen, the first input delay is 2 seconds.

A delay in the first interaction can lead to frustration and cause the user to abandon the page. Therefore, a fast FID reflects a smooth and interactive user experience. On the other hand, a slow FID indicates delays in the web page's responsiveness to user input, leading to a poor user experience and potential frustration.

By optimizing for FID, website owners can ensure that their websites are responsive and provide a positive user experience right from the first user interaction.

How is FID Different From Time to Interactive?

The Time To Interactive (TTI) metric measures how long it takes for a web page to become fully interactive after a user launches it. This is an important metric because it shows whether the web page is easy to navigate and if users can get to the content they want quickly.

The First Input Delay metric, on the other hand, measures how quickly a web page responds to a user’s first click or tap. This is a different kind of responsiveness, but it’s still important because a slow response time can lead to a poor user experience.

However, it’s important to remember that the FID metric is mostly related to the time it takes for a page to load, while the Time to Interactive metric is related to how long it takes for the page to fully load and become interactive.

How is FID Different From Interaction to Next Paint (INP)?

First Input Delay (FID) measures how quickly a page responds to a user’s input whereas Interaction to Next Paint (INP) measures how quickly the next screen in a user’s flow loads after an action.

FID measures interactiveness while INP focuses on responsiveness. Google has now replaced FID with INP as a Core Web Vitals metric alongside Largest Contentful Paint (LCP) and Cumulative Layout Shift (CLS)

First Input Delay (FID) only accounts for the first interaction. It measures only input delay, not the processing time of event handlers or the delay in displaying the next frame. In contrast, INP considers all page interactions.

This update meant that while it is essential to measure and optimize your web pages for FID, you should start measuring & optimizing INP as a Core Web Vitals metric. Read our article on how to optimize your web pages for INP.

What are the Advantages of FID?

1. First Input Delay is much more actionable than Time to Interactive as it can be used to identify and diagnose issues with your app’s performance.

2. FID is also easier for developers to implement than other performance indicators like UI Response Time or Frame Rate.

What are the Disadvantages of FID?

1. It doesn’t account for network conditions.

First input delay measures the time between a user tap and when the web page responds on screen, it doesn’t take into account any time that might have elapsed while waiting for data from a remote server.

If your web page requires a round trip from your server before displaying content to users, it could significantly increase the time they have to wait before seeing their response appear on the screen.

This could result in an increase in first input delay that isn’t representative of how responsive your web page really is under normal network conditions.

2. It doesn’t account for pre-loading content.

If your web page is retrieving data from a remote server, it may display some content while waiting for the full response to be retrieved. This could result in an increase in first input delay and give false results.

What Causes First Input Delay?

First Input Delay (FID) is caused by several factors that can impact the responsiveness and interactivity of a website. Here are some common causes of first input delay:

1. JavaScript Execution: Heavy JavaScript execution, especially long-running scripts or those that block the main thread, can cause delays in processing user input, resulting in higher FID scores.

2. Render Blocking Resources: Resources such as CSS or JavaScript files critical for rendering the above-the-fold content can also impact FID. If these resources are not optimized or are render-blocking, they can delay user input responsiveness.

3. Long Tasks: Long tasks, which are tasks that take a significant amount of time to complete, can also result in FID issues. These tasks can block the main thread and hinder user input responsiveness.

4. Slow Network Connections: Slow network connections can also cause FID problems, as resources may take longer to load, delaying the processing of a user's input.

5. Server Response Time: The server response time, including the time it takes for the server to process a user's input and send a response, can also impact FID.

What is a Good FID Score?

The first input delay measures how quickly a page responds to a user’s input. Google’s official documentation recommends sites should strive to have a First Input Delay of 100 milliseconds or less.

If you would like to ensure that most of your users are hitting this target, a good threshold to measure would be the 75th percentile of mobile and desktop page loads.

First Input Delay Scoring Metrics
First Input Delay Scoring Metrics

FID is often associated with the “loading” page of a website. A “loading” page is a page that is currently being loaded by a user’s browser, either through a click or automatically by the browser.

A low FID score will show that your content is easy to reach and quick to load. This can help you retain users and improve your ranking in the Google SERPs.

Tools to Help Measure First Input Delay

1. Google Developer Tools: Google’s Chrome browser has a built-in developer tool that can be used to measure the first input delay. This allows you to see how long it takes for a web page to load and become interactive. The developer tool also allows you to see how many resources are being loaded by the web page and whether they are blocked or not.

2. Google Analytics is a free service that can be used to collect data about website traffic, including FID data. As of this writing, the latest version of Google Analytics is v4 and it can be used on any website that uses HTML5, CSS3, and JavaScript.

3. Google’s Core Web Vitals are a set of metrics developed by Google for developers (or anyone else) who want a simple way to gather insights about their page performance without having to write code or learn complex analytics tools like Google Analytics or Flurry. It has some limitations compared with other platforms but it’s free and easy to set up, so it might be worth giving it a try if you need something simple but effective. You can see your Core Web Vitals score in your Google Search Console reports under the ‘Experience’ section.

How to Optimize Your Web Pages for FID?

1. Reduce the size of your images: Small images, as well as images that aren’t necessary for the content, can add unnecessary weight to your page. Images account for about 60% of the data transferred, so if you can reduce the size of your images without losing quality, you can reduce your page size and speed up your page.

2. Use a Content Delivery Network (CDN): A CDN is a server that stores your website’s content and distributes it across the globe. A CDN allows your website’s content to be delivered quickly because it’s being hosted across the world, not just in your region.

3. Optimize your code: Code that isn’t optimized can slow down your website. You can use tools that analyze your code and tell you where you can make improvements.

4. Leverage browser caching: Browser caching allows your browser to download and “remember” the content of your website. It saves a lot of bandwidth and time.

5. Use asynchronous loading: Asynchronous loading allows you to load your content asynchronously. This means that users will see something on their screen while the rest of the page loads.

6. Improve Server Response Time: Review and optimize your server-side code to reduce server response time. Use techniques such as caching, content delivery, and server-side optimizations to improve the speed at which the server processes user input and responds, thus reducing FID.

7. Monitor and Test: Regularly monitor and test your website's performance, including FID, using tools such as Google PageSpeed Insights, Lighthouse, or other performance testing tools. Identify any issues and make necessary optimizations to improve FID continuously.

Track Site-Wide FID Scores & Automate Optimization With Quattr

The current process of optimizing web pages for FID only allows you to optimize the scores for one web page at a time. This can be a challenge if you have a website with thousands of web pages. Existing tools do not allow you to optimize and track your FID across your entire website.

The Quattr platform addresses the shortcomings of the current process and helps you optimize your site to improve overall page experience and FID Scores. You can use the Quattr platform to view FID scores for each page of your website all at once. You can also filter pages based on whether the FID score is Good, Needs Improvement, or Poor. Quattr also lets you compare FID, and other Core Web Vital scores against your competitors in one view.

Comparing Core Web Vitals Scores Against Competitors Using Quattr
Comparing Core Web Vitals Scores Against Competitors Using Quattr

If you are looking to optimize your FID scores and improve the page experience of your entire website then Quattr’s Usability Recommendations is here to help. The performance dashboard within usability recommendations gives you a list of prioritized recommendations and performance improvements you can make across your entire site.

Usability Recommendations by the Quattr Platform
Usability Recommendations by the Quattr Platform

This list is ranked based on what key pages you should focus on and aligns optimization efforts with business metrics like clicks and conversions so that you can measure the benefits of your efforts.

Continue to Optimize First Input Delay

First Input Delay is an important metric that measures how quickly your pages respond to a user's input.

It is important to understand how it's calculated and what impacts it has on your users. In order to improve your FID, it's important to optimize your website's images, use a content delivery network, optimize your code, and use asynchronous loading to ensure your pages load quickly.

While the current optimization tools only allow you to track and optimize FID scores per web page, Quattr can help scale and automate your optimization efforts.

Optimize your FID Scores with Quattr today!

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First Input Delay (FID) FAQs

What is First Input Delay (FID) in SEO?

First Input Delay (FID) is a metric used to measure the time it takes for a web page to respond to a user’s first interaction with it, such as a click. FID is an essential metric for SEO as it measures the user experience and affects how users interact with websites. A good FID is essential for improving user experience, increasing user engagement, and improving search engine rankings.

What is a Good FID Score?

A good FID score is considered under 100ms, showing that the page can respond quickly to user interactions. A score over 300ms is considered poor and indicates that the page is not performing well and needs to be optimized.

How to Measure First Input Delay (FID)?

First Input Delay (FID) can be measured using tools like Chrome DevTools, Google PageSpeed Insights, and Lighthouse. These tools measure the time it takes for a page to respond to a user’s first input or action. Analyzing the results will help identify areas needing improvement.

How to Fix First Input Delay?

Several things can be done to fix First Input Delay (FID) issues. First, optimize JavaScript so that it only runs when necessary. Additionally, use caching to store and reuse data, reduce the number of HTTP requests, and compress CSS and HTML files. Lastly, utilize techniques like lazy loading, pre-loading, and prefetching to reduce FID.

About The Author

Rick Bucich

Rick got involved in SEO by accident 20 years ago while working at a small startup. He has 10+ years of experience in SEO and translates it into actionable recommendations. Rick writes about how to optimize and enhance websites for search engines.

About Quattr

Quattr is an innovative and fast-growing venture-backed company based in Palo Alto, California USA. We are a Delaware corporation that has raised over $7M in venture capital. Quattr's AI-first platform evaluates like search engines to find opportunities across content, experience, and discoverability. A team of growth concierge analyze your data and recommends the top improvements to make for faster organic traffic growth. Growth-driven brands trust Quattr and are seeing sustained traffic growth.

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