What Is the First Input Delay (FID)?
First Input Delay (FID) measures the time elapsed between a user’s first interaction with a webpage, such as clicking a link or tapping a button, and the browser’s ability to respond to that interaction. This metric highlights the responsiveness of a page and plays a significant role in assessing its interactivity.
The Importance Of First Input Delay (FID)
FID evaluates a website’s interactivity, directly impacting user satisfaction and retention.
Types Of First Input Delay (FID)
- Good FID: Less than 100 ms.
- Needs Improvement: Between 100 ms and 300 ms.
- Poor FID: More than 300 ms.
Examples Of First Input Delay (FID)
Delays caused by heavy JavaScript execution on a single-page application.
Best Practices For First Input Delay (FID)
- Minimize JavaScript execution time.
- Split long tasks into smaller chunks using modern frameworks.
- Implement web workers to offload tasks from the main thread.
Key Aspects Of First Input Delay (FID)
- User Engagement: Directly measures responsiveness during critical moments.
- Technical Influence: Affected by JavaScript execution and browser processing.
- Critical for Interaction: Impacts the usability of interactive elements.
Challenges For First Input Delay (FID)
- Single-page applications often suffer from poor FID due to initial JavaScript loads.
- Requires real user interaction for accurate measurement.
Relevant Metrics
- Total Blocking Time (TBT).
- Time spent on main-thread tasks.
Conclusion
Improving FID enhances website interactivity and user satisfaction, contributing to better engagement and SEO performance.
