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How To Improve The First Input Delay (FID) Score

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    By Hitesh
    March 20, 2023
    ~ 3 minutes to read
    Hitesh is a digital marketing strategist and entrepreneur with more than 15 years of experience in digital marketing, start-ups, branding, and customer acquisition strategies. Hitesh is the CEO and Founder of Reposition Group, which specialises in digital growth strategies.

    An Overview Of FID (First Input Delay)

    In Core Web Vitals, the First Input Delay (FID) metric captures an initial impression of the interaction and responsiveness of a website. A browser’s response time refers to the length of time it takes to respond to a user’s first interaction with a page.

    Here is everything you need to know about First Input Delay (FID).

    What is the first input delay (FID)?

    An example of this is the First Input Delay, which measures how long it takes for a web browser to process a user’s first interaction with a website after entering it.

    The time between these two events is called input delay or input latency.

    It is important to note that FID refers to the latency between user interactions, i.e. when a user clicks or taps on a link or a button. As soon as the browser receives your action, it begins processing it.

    An event measured by FID should be discrete to be considered user input. Using this metric cannot accurately measure continuous types of user interaction, such as zooming or scrolling. In addition, they often do not run on the browser’s main thread and are subject to different constraints.

    What is a good first input delay?

    In general, a good First Input Delay time should be less than 100 milliseconds, while the average First Input Delay time should be between 100 and 300 milliseconds, and a bad First Input Delay time should be greater than 300 milliseconds. The downside is that these add up pretty quickly on a modern website and can result in a very unpleasant user experience.

    Where is the first input delay in Light House?

    The First Input Delay (FID) is the metric shown in the performance section of the Lighthouse report.

    FID Score

    How do you reduce FID (First Input Delay)?

    First Input Delay

    Step 1: Optimise JavaScript Execution Time

    The browser will spend less time executing JavaScript when the amount of JavaScript on a web page is reduced. 

    As a result, the browser will be able to deal with user interactions quickly and respond accordingly. To boost your FID score, you should eliminate unused JavaScript, for example.

    Similarly, you may remove any polyfills that are not in use. You may not be familiar with polyfills. In older browsers, these codes are required for the site to function properly.

    Ensure that you remove only those items that are unused. If this is not the case, your website may not function correctly in commonly used browsers. It will make the user experience on your website unpleasant for visitors.

    Step 2: JavaScript tasks should be broken up into smaller parts

    When running on the main thread, the long JavaScript task mentioned in the previous section can result in the page becoming unresponsive to user input. In this regard, it is vital to break down long-term tasks into smaller pieces.

    What is the best way to determine whether a task will take a significant amount of time?

    It is considered a long JavaScript task when it occupies the main thread for more than fifty milliseconds. By separating such tasks into asynchronous ones, they will not run simultaneously. The method of reducing user input delays is an excellent one.

    Step 3: Ensure that third-party code is minimised

    The inclusion of third-party codes and tags may result in your website becoming inoperable. Consequently, input latency will increase.

    You should not include unnecessary third-party code on your website. Third-party tags may provide you with benefits, but are they worth it if they adversely affect your website’s performance? 

    It is recommended that you feature them below the fold if you still feel you need them. Therefore, the third-party tags will remain on your site without affecting the first interaction the user has with the site since they will appear only when the user scrolls down.

    Step 4: Long-running tasks should be run off the main thread

    Breaking long JavaScript tasks can help shorten input delays. However, if you prefer not to break a long-running task and improve your FID score simultaneously, here’s an alternative:

    JavaScript tasks can be run in the background by using the Web Workers API. 

    Using this method, you can keep long processes away from the main thread while still keeping them running on a separate thread. There will be no impact on the user’s interaction with your website as a result of this change.

    Step 5: Themes and plugins for WordPress should be reliable

    Your website should only be built using high-quality, trusted WordPress plugins and themes. The WordPress backend should also be cleaned of unused, unsafe plugins and themes.

    Step 6: Lazy Load Your Images

    When you enable lazy loading for images, especially those below the fold, you can free up some bandwidth for the transfer of code.

    It will reduce the time it takes the browser to execute codes and allow the user to interact with the page without having to wait for long periods.


    It may seem that First Input Delay is an inconsequential metric, but if you do not pay attention to it, it may drive visitors away from your site and may affect your search engine rankings.

    Due to the fact that FID is derived from actual user input, it is not possible to manipulate it in order to improve rankings.

    Utilise the strategies listed above to optimise input latency and improve your ranking on Google.

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