Introduction
In the fast-paced world of e-commerce, loading speed has always been king, but the way we measure user experience has changed dramatically. As of March 2024, Google has replaced the well-known First Input Delay (FID) metric with Interaction to Next Paint (INP) as part of its Core Web Vitals. This change isn’t just a technical detail; it’s the new norm for how the search engine understands a website’s responsiveness. For e-commerce owners, INP measures how quickly a page responds to any user interaction, from clicking an add-to-cart button to navigating categories. Fixit EE sees many websites falling short on this metric, often ignoring the fact that INP focuses on the overall quality of the interaction, not just the initial load.
Understanding INP: Beyond Simple Loading Speed
Interaction to Next Paint (INP) is a metric that evaluates the processing performance of a website over its entire lifespan. Unlike the older FID, which only measured the first interaction, INP collects data from all interactions on a page and reports the overall experience.
What exactly does INP measure?;
This metric combines three stages of response time: Input Delay, Processing Time, and Presentation Delay. In practical terms, if a customer clicks “Search” and the page freezes for 2 seconds before the results appear, that time is recorded as INP. Google looks at the 75th percentile of interactions, meaning it doesn’t measure extreme cases, but the experience experienced by the majority of users.
Why is the change from FID to INP critical?;
The old FID had a major drawback: it only measured the first interaction. A site could have a great FID but “hang” on subsequent clicks. INP fixes this gap by providing a more complete picture of your interaction. This is crucial for e-shops, where the user performs dozens of actions on each visit (filtering, adding to cart, resizing, paying). If the page is slow at any of these points, INP will capture it and affect the SEO score.
The Technical Challenges in E-Commerce Systems
Adopting INP requires a deeper understanding of how modern CMS and e-commerce frameworks work. Fixit EE has found that most delays arise from excessive JavaScript usage and computational load on the browser's Main Thread.
The impact of JavaScript and Plugins
On platforms like Magento and WooCommerce, installing multiple plugins for tracking, chatbots, or dynamic pricing often fills the main thread with scripts. When the user clicks, the browser must finish executing the running scripts before responding to the user’s command. This delay is the main cause of bad INP. The solution is not just to reduce the number of plugins, but to optimize the way they are loaded and executed.
Modern solutions: Lazy Loading and Web Workers
To improve INP, it is necessary to move heavy tasks outside the main thread. Using Web Workers allows computational tasks to be performed in the background, leaving the main thread free to respond immediately to user interactions. Furthermore, proper Lazy Loading is not only applied to images, but also to script blocks that are not directly necessary for the first interaction. This technique ensures that the page remains responsive even on lower-performance devices.
Practical Optimization and Results Analysis
INP optimization is not a one-time task, but a continuous process of monitoring and improvement. It requires a combination of diagnostic tools and technical code refactoring.
Diagnostic Tools: From Lighthouse to Real User Monitoring
Google Lighthouse provides a great insight into a test environment, but INP relies on real user monitoring (RUM). Tools like Chrome User Experience Report (CrUX) and PageSpeed Insights provide real-world data. It’s important to focus on this data, as it represents the behavior of your real customers, who may have slower connections or older devices than your development environment.
Improvement Strategies for Magento and WooCommerce
In Magento environments, using Varnish Cache and optimizing Full Page Cache are fundamental. However, INP focuses on the client-side. Here, minimizing blocking resources and using the “Defer” technique for scripts that are not critical for rendering are necessary steps. For WooCommerce, avoiding heavy AJAX calls during navigation and adopting “Event Delegation” for event handlers can dramatically reduce processing time.
Fixit Tip: Don't just focus on reducing the size of the JavaScript file. Often, bad INP is caused by many small scripts running simultaneously on the main thread. Prioritize decongesting the Main Thread.
INP Optimization Summary
Understanding and optimizing INP requires a strategic approach that combines technical knowledge with an understanding of the user experience. Below is a comparison table between the old and new approaches.
| Parameter | Old Metric (FID) | New Metric (INP) |
|---|---|---|
| Focus | First interaction | All interactions on the page |
| Measurement | Time from click to start of processing | Time from click to next image |
| Data | Virtual test (Lab Data) | Real user data (Field Data) |
| SEO impact | Minimal/One-dimensional | Important (Core Web Vital) |
Making INP a priority is not just a matter of complying with Google standards. It is a matter of business consistency. An e-shop that does not respond promptly to user commands loses sales, no matter how well-designed its advertising campaign is. Fixit EE specializes in developing high-performance e-commerce solutions, both in Magento and WooCommerce, incorporating modern optimization practices from the code base. Contact us to evaluate the performance of your e-shop and design an optimization strategy that will enhance the customer experience and your organic ranking.
