Contents
What is First Contentful Paint (FCP)?
This First Contentful Paint metric measures the passage of time from when a user walks into navigation to when the first content appears on the screen. This content might be text, image, or any visual element that gives users an initial impression that the page is loading. FCP is one of the first indicators of perceived page load speed and is part of Google’s Core Web Vitals.
FCP does not, however, measure interactivity. It solely indicates when users see visual feedback, giving them assurance that the page is actively loading. Sites with a brief FCP can positively impact user perception of site performance and reduce bouncing.
How FCP is Measured:
– The FCP is measured as the time between navigation of the page and rendering the first visible element onto the screen.
– This measurement disregards content rendered onto the screen after the first visible element, or any user interaction afterward.
Why FCP Matters:
– Perceived Load Speed: A quick FCP can improve perceived performance by showing users something on the screen as soon as possible.
– User Engagement: FCP can help determine if users are likely to wait for additional content, but it’s only the first step toward a responsive experience.
—
What is Interaction to Next Paint (INP)?
Interaction to Next Paint (INP) is one of the newest metrics offered by Google under its expanded Core Web Vitals. It measures the overall responsiveness of a page, i.e., the time taken by the browser to react to a user’s interaction and update the visible content. Thus, INP measures the latency in user input-performance feedback-video input feedback with respect to input mechanism-but actually from clicks, taps, and keystrokes to the visual feedback that the user sees on the video input.
How INP is Measured:
– INP considers and tracks longest way of any interaction latency on a user session on a page.
– This includes clicking, tapping, or keyboard events as these are usually typical user interactions.
– It measures the time from user interaction to when the browser is able to start its visual response, giving a more holistic perspective of interactivity for a page.
Why INP Matters:
– User Interactivity: INP is much more correlated with actual user behavior because it measures how fast a page responds to the users’ actions-secondwise, which is a key indicator of user experience.
– Performance Evaluation: While FCP might be telling a user that the page is loading, INP tells the user if the page is able to sustain continuous interactions, which is a big factor in user engagement and satisfaction.
—
Key Differences Between FCP and INP
Even though both FCP and INP prove to be vital web performance metrics, they measure different aspects of the user experience and are, therefore, used for different purposes.
Why Both FCP and INP Matter for User Experience
Load speed and responsiveness of a website are the two factors critical to a good user experience, each affecting the user in a different way:
- Reducing User Uncertainty: FCP indicates that the page is definitely on its way. In the first phase, the display of the first visible element helps in having the feeling that the blank page will soon cease to exist. This would assure the users.
- Ensuring Smooth Interactivity: INP helps ensure that users can engage with the content without delay or lag, which is particularly important for interactive sites, such as e-commerce and social media platforms. Poor INP scores may result in users perceiving a site as sluggish, leading to frustration and possibly abandonment.
- Complementary Insights: While FCP is excellent for assessing the initial load experience, it cannot account for ongoing interactivity. INP fills this gap by showing how well a page responds once users start engaging with it.
—
Best Practices for FCP and INP Optimization
The following best practices are put forth to be considered in a way that enhances FCP and INP scores:
For FCP Enhancements:
– Protect the Critical Rendering Path: Minimize the render-blocking resources like CSS and JavaScript above the fold.
– Async Load Scripts: Any scripts that are not crucial can be loaded asynchronously or be deferred, so their execution does not intervene with the paint.
– Compress Images & Use Next-Gen Format: Compress the images with the proper format, say WebP, and set the proper dimensions.
For INP Enhancements:
– Reduce JavaScript Execution Time: The fewer JavaScript runs, and things happen on the main thread, the more responsive it is.
– Optimize Event Handling: Optimize user interaction event handling. For example, if scroll events can be called too frequently, use either throttling or debouncing.
– Optimize Third-Party Scripts: Third-party scripts may be hindering responsiveness. Use only those that are absolutely required, and if possible, load them asynchronously.
—
How Can Google Measure FCP and INP through Its Tools?
A few Google tools provide users with visibility into FCPs, INPs, and other Core Web Vitals:
- PageSpeed Insights: The all-encompassing tool assigns scores for FCP, INP, and other Core Web Vitals and suggests how scores could be improved.
- Lighthouse: Lighthouse, being part of Chrome DevTools, generates a detailed report for FCP and INP so developers can diagnose and optimize these metrics.
- Google Search Console: In the Core Web Vitals report, Search Console gives a site-wide overview of FCP and INP issues so that prioritization of optimization efforts may be done.
Two major but different aspects of web performance that are concerned respectively with FCP and INP are considered. During INP, the aim is to keep user interaction smooth and responsive over a period of time, while FCP governs the perception of load speed by showing some content during delivery. Optimizing both offers the best user experience, which promotes user engagement and satisfaction and, thereby, leads to achieving a higher ranking in search listings.
By looking into FCP and INP and optimizing them, developers and website owners create a rather interesting and very fast web interface for modern users and search engines.