Project Leyden aims to improve startup time, time to peak performance, and the footprint of Java programs by selectively shifting work out of the startup phase of the program. How can it improve startup while respecting the amazing dynamic behavior of the Java platform? By relying on the same techniques that have fueled Java’s peak performance for years and years: speculative optimization. JEP 483: “Ahead-of-Time Class Loading & Linking” in JDK 24 is the first instalment of this effort with more to follow. Join us as we explore how Leyden shifts work ahead of time based on speculating that future executions will be similar to previous executions of your program.

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