What Is Total Blocking Time (TBT)?
TBT measures the total time during which the main thread is blocked, preventing user interaction. It is a key metric in assessing the responsiveness of a webpage.
The Importance Of Total Blocking Time (TBT)
Reducing TBT improves interactivity and user experience, increasing engagement and better Core Web Vitals scores.Learn more: How To Evaluate Your Core Web Vitals (CWV) Health
Learn more: What Happens If Core Web Vitals (CWV) Are Not Optimized?
Examples Of Total Blocking Time (TBT)
- Heavy JavaScript bundles causing TBT spikes.
- Optimized pages with TBT below 200 milliseconds.
Best Practices For Total Blocking Time (TBT)
- Split large JavaScript bundles into smaller chunks.
- Defer non-critical scripts.
- Use web workers to offload tasks.
Key Aspects Of Total Blocking Time (TBT)
- Thread Management: Minimizing long tasks on the main thread.
- Code Splitting: Reducing the size of initial script loads.
- Third-Party Scripts: Mitigating their impact on performance.
Challenges For Total Blocking Time (TBT)
- Identifying and fixing long tasks in legacy codebases.
- Balancing functionality with performance.
Relevant Metrics
- Total Blocking Time (milliseconds).
- Long tasks count.
