What Are the Best Practices for Managing Third-Party Scripts to Minimize Their Impact on Interaction to Next Paint (INP)?


Effectively managing third-party scripts is critical for minimizing their impact on Interaction to Next Paint (INP). Best practices include loading scripts asynchronously, deferring non-essential scripts, reducing the number of third-party requests, and utilizing browser performance features such as preconnect and prefetch. This comprehensive guide outlines these strategies in detail.

Asynchronous Loading of Scripts

Load Non-Critical Scripts Asynchronously

Use the <script async> attribute to load third-party scripts that are not critical for rendering the above-the-fold content. This prevents these scripts from blocking the parsing of the HTML document [Efficiently Load Third-Party JavaScript, 2020].

Defer Non-Essential Scripts

Use the <script defer> Attribute

The defer attribute ensures that the script is executed only after the HTML document has been fully parsed. This is beneficial for scripts that modify the DOM or are not immediately required upon page load [Defer Non-Critical JavaScript, 2023].

Reduce Third-Party Script Requests

Minimize the Number of Requests

Each third-party script added to a page introduces additional network requests which can slow down the loading process. Evaluate and reduce the number of third-party scripts to minimize their impact [Minimize Third-Party Scripts, 2022].

Utilize Performance Optimization Techniques

Preconnect and Prefetch

Use <link rel="preconnect"> to establish early connections to third-party origins, and <link rel="prefetch"> to fetch resources that are not immediately needed but likely to be used in future navigation. This can help in lowering the time taken to establish connections [Preconnect and DNS Prefetch, 2022].

Code Splitting and Lazy Loading

Implement code splitting to divide the bundle into smaller chunks, and lazy load scripts so they are only loaded when needed. This reduces the initial load time and resource usage [Lazy Loading Best Practices, 2020].

Monitor and Optimize Script Execution

Performance Monitoring Tools

Use tools like Chrome DevTools and Lighthouse to monitor third-party script impacts on performance. These tools offer insights into slow-loading elements and suggestions for optimization [Lighthouse, 2022].

Resource Hints

Implement resource hints such as <link rel="dns-prefetch"> to optimize the retrieval of resources. This can improve the efficiency of third-party scripts by pre-resolving DNS queries [DNS Prefetching, 2021].

Example Strategies

Lazy Load Third-Party Widgets

Implement lazy loading for third-party widgets such as social media buttons or comment sections that do not need to be loaded immediately. This can significantly reduce the initial load time and improve INP [Use lazysizes to lazyload images, 2020].

Optimize Analytics and Advertising Scripts

Analytics and ad scripts can be particularly heavy. Use asynchronous loading and defer these scripts where possible. Additionally, consider using tag managers to control how and when these scripts are triggered [Efficiently Load Third-Party JavaScript, 2023].


Managing third-party scripts effectively is essential for optimizing Interaction to Next Paint (INP). By adopting these best practices—such as asynchronous loading, deferring non-critical scripts, minimizing third-party requests, and using performance optimization techniques—developers can greatly enhance the performance and responsiveness of their web pages.