Using synchronous functions in a Node.js application can block the entire web development process by halting other operations until the current task is finished. This can lead to performance issues, especially in high-traffic applications. To catch these problems early, it’s helpful to use the –trance-sync-io flag. This flag warns you whenever synchronous code is detected, allowing you to spot and replace it with asynchronous alternatives. Asynchronous APIs allow multiple tasks to run without waiting for each to finish, keeping your application responsive. While async functions may seem complex at first, they’re essential for smooth logic flow in modern Node.js apps. During testing, async functions help expose potential performance bottlenecks by showing warnings and stack traces. In short, avoiding synchronous functions improves performance, scalability, and overall user experience—key aspects of a professional Node.js web development process.