Java 8 introduced several key features that significantly enhance application development by improving readability, simplifying code, and enhancing performance. Lambdas and functional interfaces facilitate cleaner, more concise code, especially when manipulating collections with the Stream API. This allows for more expressive and efficient data processing patterns. Optional class helps in better handling of null values, reducing the chances of NullPointerExceptions. The introduction of CompletableFuture makes it easier to write non-blocking, asynchronous code, improving application responsiveness. Additionally, Java 8's new Date and Time API offers a more intuitive and flexible way to handle time operations, addressing the shortcomings of the older java.util.Date and Calendar classes. These improvements not only boost developer productivity but also enhance application performance and maintainability.