What is First Input Delay (FID), And How to Optimize It?

Team TypeStack
Team TypeStack ...
Dec 07, 2022  . 8 min read
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How to fix first input delay - TypeStack
How to fix first input delay - TypeStack
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What is FID and why is it important? Before we deep dive into it, here’s something you should know. Back in June 2021, Google made the first input delay (FID) one of the important metrics in Core Web Vitals.

It’s because making the first good impression through a web page has become crucial. Imagine a user landing on your web page for the first time. How will you make a long-lasting impression on him? By making sure he has a good user experience.

A bad user experience can give them a reason to leave your page and never come back. Factors like visuals, web design, speed, and responsiveness play a crucial role in improving the user experience.

While you cannot measure your site design, responsiveness and speed can be. Therefore, First Input Display has become one of the important metrics to measure because it directly impacts your search engine results. So, let’s take a detailed approach to understand what is FID and the need for it.

What is the First Input Delay?

First Input Delay is a Web Core Vital metric that tracks the time when the user first interacts with your website to the time when the browser starts processing it. The first interaction can be actions like tapping a button, clicking on a web page’s link, or using a custom.

Google highly encourages website owners to improve their site’s responsiveness and speed to rank on top of the search engine results. The better the user experience, the higher you will rank on Google searches. The worse the user experience, the lower your website will be on Google searches.

The first user interaction plays a crucial role here. Therefore, it is important for marketers to track their website performance score and achieve at least the minimum number. Now that you understand what is FID and its importance, let’s know the good FID score.

What is a Good First Input Delay Score?

The FID score is measured in milliseconds. You need to ensure that you hit the perfect score.

For example, an FID of 100ms or less is considered good. FID of 100 - 300ms needs improvement. And an FID of more than 300ms is considered poor website performance.

Therefore, if your FID goes above 300ms, know that your website is either loading slowly or is not responding rightly to the users. It needs quick fixing to improve the user experience and rank higher on the search results.

Difference Between First Input Delay vs Time to Interactive

Marketers often confuse both these terms because both metrics are used to measure the time on the website; however, there is a thin line difference that you need to measure in order to get the right results.

Time to Interactive (TTI) is used to measure the time a web page takes to be fully interactive. Whereas, the First Input Delay is the metric used to measure the time to respond to the first user interaction.

It is believed that for once a website can have a bad TTI score, but not the First Input Delay score. FID is a unique metric that allows and motivates you to develop a website that is responsive, high in quality, and has an excellent user interface.

Therefore, it is important to focus on achieving a good First Input Delay score in order to have a good user experience and higher search result rankings.

Understanding FID in Detail

Apart from the Largest Contentful Paint, it is the First Input Display that Google wants to focus on and make it an official ranking factor on search results. But remember, not all web pages need to be FID optimized.

It’s because not every web page consists of interactive elements. A page without interactive components automatically becomes irrelevant to the First Input Delay. Well, the reason is simple — The First Input Delay majorly focuses on the responsiveness of a website and not merely scrolling or zooming.

FID measures the delay in event processing and not the time that the browser takes to load the entire page.

You can use the following tools to measure and monitor the First Input Delay:

  • PageSpeed Insights
  • Search Console
  • Chrome User Experience Report
  • Web Vitals JavaScript Library

It is a field metric as it requires real user interaction to get registered as an input event and monitor & measure it accordingly.

How to Fix First Input Delay?

There will be times when you will not be satisfied with your final First Input Delay Score. There can be numerous reasons behind it. But these problems will need quick fixing for a great user experience.

Here’s how to fix the First Input Delay and increase your final FID score.

Defer JavaScript

JavaScript is not considered an excellent practice to get a good Final Input Delay score. In fact, it is one of the reasons for the long input delay. So, you can either minimize or defer JavaScript code.

For example, JavaScript codes often take too long to execute. Because of a long time period, the page speed slows down and negatively affects the performance of your website.

The following are the ways you can implement to either minimize or defer JavaScript code:

  • Reduce unused JavaScript
  • Compress the JavaScript code
  • Leverage server-side rendering to generate quality content
  • Eliminate duplicate modules in JavaScript bundles
  • Reduce the execution time of JavaScript

Leverage Browser Cache

Using a browser cache is a great way to fix your First Input Delay. It helps in increasing the web page load speed of a user’s next visit faster than his first visit to the website.

Caching allows web pages to store data of all the websites or web pages visited by the users temporarily in the web browsers. In simple words, using a browser cache can help you in improving and speed up browsing.

For example, let’s say you visited a content marketing website. Now the job of the browser will be to take the pieces of the website you have visited and store that data on your local drive. Some of the data that this feature can store is JavaScript, CSS, HTML, and Images including logos, backgrounds, and more.

Browser cache allows you to retrieve important files from your drive faster as compared to a remote server. Therefore, leveraging the feature of the browser cache is an excellent strategy to fix and optimize your First Input Delay.

Optimize CSS Code

Your CSS code can highly impact the final FDI score. Optimizing CSS code the right way will make your website look excellent, improve the web page load speed, and positively affect your user experience.

Whereas an unoptimized CSS code negatively impacts your website’s performance and slows it down your website. Therefore, here’s how you can rightly optimize your CSS code and improve your website;

  • Eliminate unnecessary font styles
  • Minify, compress, and cache the CSS code
  • Reduce CSS file size
  • Download CSS faster
  • Lazy load CSS

Understanding the working of CSS is important as it is an excellent practice in improving the entire web performance. Thus, make sure you optimize your CSS code whenever you try to fix the First Input Delay.

Use Lazy Loading

Lazy loading is a technique of delaying the loading time on the website unless and until they are actually needed by the users. To put it simply, this process loads text or images only when the user is ready to consume the data.

It is an effective optimization technique to minimize or reduce the web page load time and serves content to users only when they request it.

Moreover, lazy loading is an excellent strategy to identify non-critical resources and load them only when it is necessary.

Eliminate Third-Party Scripts

Another factor that can negatively affect the First Input Delay and reduce your score is the third-party scripts. These third-party scripts can include Google Analytics, Social Widgets, and more.

Although it is advised to eliminate third-party scripts; however, if you still choose to go with them, here’s what you should do — Remove and add these scripts in a sequence. Check your First Input Delay Score every time you add a script. It will help you in identifying the third-party scripts that are contributing to reducing your overall score.

Once you understand what is FID, make sure you leverage these practices to improve your FID score and fix your First Input Delay.

Final Thoughts

Now that you know what is FID and the need to leverage it, make sure you optimize the adobe-mentioned tips accurately. FID is an important metric under Core Web Vitals to help your website create a long-lasting impression on the users.

User experience, web page loading speed, and website responsiveness make a lot of difference. And the First Input Delay helps you in identifying these and optimizing them to get great web results.

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