The Browser's Main Thread Is Expensive

The browser's main thread handles nearly all computational, rendering, and event-handling tasks, making it a bottleneck when overloaded with work. While main thread optimization is often overlooked in favor of network and bundle size improvements, it becomes critical in interactive applications with heavy data streams, animations, and user input, where a blocked main thread causes noticeable stuttering and lag. The article explores strategies for managing this expensive resource through splitting work, batching tasks, prioritizing operations, deferring non-urgent work, or moving tasks to other threads and the compositor.