Fast Refresh`, `Absolute Imports and Aliases`, and `Web Vitals Reporting` are new features in Next.js 9.4, bringing improvements to hot reloading, import management, and performance optimization respectively. With these updates, developers can expect more accurate error locations, preserved application state during hot reloading, and easier debugging. Additionally, Next.js now supports custom module aliases, allowing for cleaner and more organized imports. The new `Web Vitals Reporting` feature provides a unified way to measure key performance metrics, enabling developers to optimize their projects for better user experience.