Project Valhalla, Explained: How a Decade of Work Arrives in JDK 28

Project Valhalla, a decade-long effort to improve Java's performance, is being integrated into JDK 28 as a preview feature, allowing developers to write classes that behave like primitives for better memory efficiency. The integration adds over 197,000 lines of code, though this represents only the first phase of the project, which aims to solve Java's "fluffy" memory layout problem by enabling dense data storage similar to primitive types rather than scattered heap references. The project addresses the growing gap between CPU and memory speeds by allowing value objects to be stored contiguously in memory, reducing cache misses and improving performance at scale.