Summary: The article discusses how to reduce Total Blocking Time (TBT) on websites, which can lead to improved user experience and search engine ranking. TBT measures the sum of the blocking portion of all long tasks on the browser’s main thread between First Contentful Paint (FCP) and Time to Interactive (TTI). The article suggests two ways to reduce TBT: do less work on the main thread or break up long tasks into smaller tasks that don’t exceed 50ms. Removing unnecessary JavaScript is one way to decrease TBT, and the article provides an example of how a piece of JavaScript on Wikipedia's mobile site was responsible for a long task that could take over 600ms to execute during page load on low-end devices, effectively blocking user interactions. The article walks through the steps taken to reduce the execution time of this task by about 50%.