When it comes to website performance, speed and responsiveness matter a lot. One important metric that affects how users feel about your site is called First Input Delay or FID. It measures how quickly your website responds when someone first tries to interact with it.
If your site is slow to react, visitors might get frustrated and leave.
In this guide, we will explain what First Input Delay is, why it matters, and most importantly, how you can improve it step by step.
What is First Input Delay (FID)?
First Input Delay is one of the on-page SEO elements that measures the amount of time between when a user first interacts with your webpage and when the browser responds to that interaction. Interactions include clicking a link, tapping a button, or entering text in a form. FID measures how fast your website reacts to these actions.
For example, imagine you click a button on a website and nothing happens for a few seconds. This delay is what FID measures. A shorter FID means the website feels quicker and more responsive, while a longer FID can lead to a bad user experience. Websites with good FID scores feel smooth and engaging.
How First Input Delay Works
When you open a webpage, your browser does a lot of work behind the scenes. It loads HTML, CSS, JavaScript, images, and more. Some parts of this process can block the browser from responding to user inputs.
For instance, if a heavy JavaScript task is running, the browser might be busy and unable to react to clicks or taps immediately.
So, First Input Delay happens because the browser is busy processing other things and cannot respond quickly to your action.
For example, if a website uses a lot of JavaScript to create animations or load content, it might cause a longer FID because the browser’s main thread is tied up. Reducing these delays can make your site feel faster and easier to use.
What Is a Good FID Score?
Google suggests that a good First Input Delay score is less than 100 milliseconds. This means the browser should respond to user interactions within a tenth of a second. Scores between 100 and 300 milliseconds need improvement, and anything over 300 milliseconds is considered poor.
Having a good FID score is important because it directly impacts user satisfaction and engagement. Fast responses make visitors more likely to stay on your site, explore more pages, and convert into customers. Slow responses can increase bounce rates and hurt your search rankings.
Many factors influence how quickly SEO shows results, and having a good First Input Delay score helps by improving user experience, which search engines value when ranking your site.
How to Measure First Input Delay (FID)
1. Google PageSpeed Insights
Google PageSpeed Insights is a free tool that analyzes your website and provides detailed reports, including FID. Just enter your URL, and it will show your site’s performance scores and suggestions to improve. This tool is beginner-friendly and easy to use.
PageSpeed Insights combines real-world data from users and lab data from tests to give a clear picture of your website’s speed and responsiveness. It also highlights specific issues that cause delays in interaction.
2. Google Search Console Core Web Vitals Report
Google Search Console offers a Core Web Vitals report, which includes FID data for your site. This report shows how real users experience your site over time. It helps you spot pages with poor FID so you can prioritize improvements.
If you manage multiple pages or a large site, this report is handy to track FID performance across your whole website and monitor progress as you optimize.
3. Chrome User Experience Report
The Chrome User Experience Report collects performance data from real users of the Chrome browser. It includes FID along with other metrics and gives insights based on actual visitor experiences.
This report is useful to understand how your site performs in the wild, not just in lab tests. It provides a realistic view of user interactions on your site.
4. Web Vitals JavaScript Library
If you want to track FID yourself, you can use Google’s Web Vitals JavaScript library. This tool lets you measure FID directly on your website by collecting data from real visitors.
Using this method requires some coding knowledge but offers accurate and customizable insights into your site’s responsiveness.
5. Lighthouse Performance Audit
Lighthouse is a tool built into Chrome DevTools that runs SEO audits on your web pages. It provides detailed performance metrics, including FID. It simulates user interactions and shows how your page responds.
Lighthouse is great for developers who want a deep dive into site performance and want to catch issues during the development process before launching changes live.
How to Improve First Input Delay?
1. Minimize JavaScript Execution
Heavy JavaScript is often the main cause of slow First Input Delay. Try to reduce the amount of JavaScript your site uses and optimize the code you do have. Breaking up large tasks into smaller ones helps the browser stay responsive.
You can also remove unnecessary scripts and delay non-critical JavaScript from loading immediately. This reduces the work the browser has to do when a user first interacts with your page.
2. Use Code Splitting and Lazy Loading
Code splitting divides your JavaScript into smaller chunks that load only when needed. Lazy loading delays loading parts of your site until they are required, such as images or content below the fold.
These techniques reduce the initial load and help the browser respond faster to user inputs, improving FID.
3. Optimize Third-Party Scripts
Many websites rely on third-party scripts like ads, chatbots, or analytics. These can block the browser and increase FID. Review all third-party scripts and remove any that are not essential.
For necessary scripts, try loading them asynchronously or deferring their execution to avoid blocking the main thread.
4. Implement Server-Side Rendering (SSR) or Static Site Generation (SSG)
With headless websites, pages are often built using JavaScript. The problem? Search engines sometimes struggle to read those pages. That’s where SSR or SSG comes in; they make sure your pages are already complete before being shown to users or search engines.
This means Google can easily crawl and understand your content, helping you show up in search results.
5. Reduce Main Thread Work
The browser uses a main thread to process user interactions, JavaScript, and rendering. If this thread is busy, your FID will be high. Use performance tools to identify what tasks take up the most time on the main thread.
Try to simplify your code, remove unnecessary work, and avoid long tasks to free up the main thread for faster responses.
6. Use Web Workers
Web Workers allow you to run JavaScript code in the background, separate from the main thread. This means heavy computations won’t block user interactions.
By moving complex tasks to Web Workers, your page can stay responsive and reduce First Input Delay.
7. Optimize CSS and Fonts
Although CSS and fonts do not directly affect FID as much as JavaScript, poorly optimized styles can slow down rendering and cause delays in interaction readiness. Minify your CSS files and use font-display options to control how fonts load.
Faster rendering means the browser can become interactive sooner, which helps improve FID.
Conclusion On How To Improve First Input Delay
First Input Delay is a key part of how users experience your website. A fast and responsive site keeps visitors happy and improves your search rankings. By measuring your FID and applying the steps we covered, like minimizing JavaScript, using SSR, and reducing main thread work, you can make your site feel much quicker. Improving FID might take some work, but the payoff is worth it for better engagement and more traffic.
If you want expert help to boost your website’s speed and improve important metrics like First Input Delay, BestSEO is here for you. Our services focus on performance optimization and user experience to help your site rank higher and keep visitors coming back. Get in touch with BestSEO today and watch your online presence grow!
Schedule a free strategy session right now!
Frequently Asked Questions About How To Improve First Input Delay
What Is First Input Delay In Simple Terms?
It is the time your site takes to respond when a user first interacts, like clicking a button.
Why Is First Input Delay Important?
Because slow responses frustrate users and can cause them to leave your site.
How Can I Check My Website’s FID ?
Use tools like Google PageSpeed Insights, Google Search Console, or Lighthouse to measure FID.
Does JavaScript Affect FID ?
Yes, heavy JavaScript can block the browser and cause longer delays.
Can Improving FID Help SEO?
Yes, Google considers FID in its Core Web Vitals, which impact search rankings.
