Total Blocking Time: Understanding TBT and Core Web Vitals

Total Blocking Time (TBT) measures the responsiveness of a webpage during loading by evaluating how long the main thread is blocked, preventing user interactions. It's crucial for user experience and search engine rankings. High TBT can cause delays in interactivity, frustrating users and negatively impacting website performance. It's also linked to Core Web Vitals metrics like Largest Contentful Paint (LCP) and First Input Delay (FID). Common causes of increased TBT include heavy JavaScript execution, unoptimized third-party scripts, inefficient rendering, and large tasks. Optimizing TBT involves reducing main thread blocking time by minimizing JavaScript payloads, deferring non-critical scripts, reducing third-party script load, and streamlining code. Tools like Chrome DevTools Performance Panel and Lighthouse Suggestions can assist with identifying and addressing issues affecting TBT. A good TBT score is less than 200 milliseconds, ensuring a fast and responsive website. Improving TBT enhances user experience, search engine rankings, and Core Web Vitals metrics. By understanding TBT and implementing optimization techniques, developers can create websites that perform better and meet user expectations. Measuring TBT in a controlled lab environment using tools like Lighthouse is recommended. Addressing TBT issues leads to faster loading times, reduced interactivity delays, and overall improved website performance.