Many modern applications and tools rely on Java. Yet, their startup time and time-to-peak performance remain challenging, especially for microservices and Kubernetes workloads that require fast scaling and responsiveness. Project Leyden, an ambitious OpenJDK initiative, aims to overcome these performance bottlenecks.

In this session, Ana will show how you can take advantage of Leyden’s optimizations using Java 25 to transform the scalability and responsiveness of your application. Empower yourself with practical techniques you can apply today, along with a peek into the ongoing work inside Leyden and what that means for the performance of your Java application.

Devoxx

A conference talk covering Project Leyden and JVM startup/warm-up performance improvements in JDK 24, 25, and 26. The speaker explains the AOT (ahead-of-time) cache workflow — including three-phase and two-phase approaches — and how training runs using integration or smoke tests can significantly reduce startup time (up to 66% improvement). Practical guidance is provided for Spring Boot users, including unpacking nested jars with jar-mode tools, aligning training runs with production class loading, and deploying AOT caches in containers. JDK 26 improvements address GC compatibility (G1 vs ZGC) with baseline AOT caches. Benchmark data from Spring Pet Clinic shows real-world gains in startup time, memory footprint, and time-to-first-request when combining JVM AOT cache with Spring AOT.

[VDBUH2026] Ana-Maria Mihălceanu - Supercharge your JVM performance with Project Leyden