What Is First Input Delay and How To Fix It

The first input delay is the time it takes to process a request from the first request to the first byte that is available.

A request is a message that a web browser sends when it wants to go to a specific address. The first request is the first request sent to the server.

It contains the requested address of the page that you want so that the server knows which page to render and where to send the response.

Today you will learn how to fix this first input delay error and how to check-in tools to improve this performance.

What is First Input Delay

The first input delay is the time it takes to process a request from the first request to the first byte that is available. This time can be divided into two parts: the processing delay and the transmission delay. The processing delay is the time it takes to process the request, parse the response, and generate the output. The transmission delay is the time it takes to send the request and receive the response.

Let us discuss this first input delay using an example so that you can easily understand it.

Just think that you are in the forest and a tiger comes in front of you, what will you do now? Your mind will freeze for some time. Then after a few seconds, your brain will work. Hey, Tiger is coming here, run away from here soon.

Now when you see the tiger and run after seeing the tiger. The time between you seeing the tiger and running away from that place, that time is the first input delay.

How to Measure First Input Delay (FID)

When your visitor visits your site and after loading all content of your site he will click on some link or element. FID is not that time when the action occurs after clicking the button. FID is the time when the site starts working after clicking on the button.

So FID means how long it takes to register user touch, tap, or click and how that click is taking action on that.

How First Input Delay (FID) Works

Google notes your FID score in milliseconds. If your FID score is in 100ms then it is good. If your FID is 300ms then you need to improve it but if your FID score is 300ms higher then it will show poor performance.

You cannot see your website FID score in page speed insight or any other tool. Google notes your FID score using field data means that it collects data from live users when they click on a link.

Total Blocking time(TBT)

You can check your FID score using TBT. If your TBT score is good, then your FID score is also good.

Why is First Input Delay a Good Metric for Improving Performance?

Because it is simply a Real User Metric, First Input Delay is one of the most intriguing web performance indicators. It is impossible to simulate in a lab test since user engagement must be measured. FID is all about the user’s real experience when they land on your page.

It’s a wonderful measure to track and optimize for that reason alone, as it defines your website’s User Experience.

From an SEO sense, it’s now official that First Input Delay will begin to impact your website’s rankings.

First Input Delay is one of three performance indicators that Google intends to promote with its Core Web Vitals effort (together with Cumulative Layout Shift and Largest Contentful Paint).

The statistic that measures a website’s responsiveness is First Input Delay, while CLS measures visual stability and LCP measures loading speed.

When the Page Experience update goes live, Google plans to incorporate Core Web Vitals into its ranking system.

In other words, there are numerous reasons to optimize your website’s First Input Delay.

How Improve Your First Input Delay

When you work on improving the TBT score, your FID will also be fixed.

  • Reduce JavaScript Execution Time
  • Optimize CSS
  • Minimize Main Thread Work
  • Reduce Third Party Code
1. Reduce JavaScript Execution Time

Your site will not respond until all the JavaScript on a page is loaded. So use as much JavaScript as required. Minify or delete unused JavaScript. We already discussed in the last LCP blog how to minify JavaScript.

2. Optimize CSS

There are many CSS files in our website, which is unnecessary, which makes no sense. To fix this, we can minify all CSS files. When we minify a file, we remove all unnecessary characters from the code, which reduces the file size and makes the code easier to read.

3. Minimize Main Thread work

When the browser loads your website, the backend loads a lot of processes that are stuck in a lot of threads, one of them is the main thread which works more like creating DOM, executing JavaScript, etc.

The browser will not allow the user to input for as long as it remains busy. You will also find a way to solve this in Page Speed Insight.

Minimize main thread work

In this image, you can see how much time the main thread is taking.

4. Reduce Third Party Code

Third-party code is code that comes from outside in your website like google analytics, chat using this website, they will add some dynamic code to your website.

All these things increase the time of your website. To make it work, you use the third-party code that is required for you.

If your competitor is using a third-party tool, it does not mean that you should also use it. Use only if you need this functionality.

So this FID is a little bit up down metric but if you work on all these things then your FID score will get better.

Important Point 

When a visitor visits your website, the browser first loads all the content from the bottom of your website and then slowly loads the top part but the visitor wants to read the top part first.

When your website loads it completely using any browser it loads the first bottom section of your website then the top part but the user needs the top part first.

For this, you can tell your developer to save the upper part in a separate folder and save the lower part in a different folder so that when someone opens your site, the top part is visible to the visitor first. By the time he reads the top part, the lower part will be loaded automatically.

If anyone visits your website, it starts reading from higher than and doesn’t run down right away and if you’re saving and loading the highest part of your website in an exceedingly separate folder, then there’s no downside with loading speed before the user can return and also the loading speed and performance of your web site can stay sensible.

Conclusion :

Google recently updated its Corel Web Vital to improve its CLS, FID, and LCP scores and improve your mobile performance.

If you have worked on the following point then you can easily fix your first input delay. I hope you guys have understood this blog post. If you like this post, you can share it with your friends.

Rishabh Kolhe
Rishabh Kolhe
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