Guest: Simon Ritter (LinkedIn)
Company: Azul 
Show: Java Reloaded
Topic: Cloud Native

Performance has always been one of Java’s defining strengths, and JDK 25 raises the bar once again. In this short clip, Simon Ritter, Deputy CTO at Azul, explains how the latest release introduces two key features designed to make Java faster, leaner, and more efficient: Compact Object Headers and Ahead-of-Time (AOT) optimizations.

Compact Object Headers address a long-standing challenge in memory efficiency by reducing the space used in the heap. Ritter shares that in benchmark tests, applications saw up to a 22% reduction in heap usage and an 8% decrease in CPU consumption. These improvements directly translate to cost savings and smoother performance — particularly in enterprise environments running large, distributed Java workloads.

The second major advancement, Ahead-of-Time (AOT) optimization, tackles another critical area: startup time. Traditional Java applications go through a “warm-up” phase where frequently used code is compiled on the fly. AOT changes that by taking a snapshot of the application once it reaches optimal performance, allowing subsequent starts to reuse that data and launch much faster. This is especially useful in microservices architectures, where instances spin up and down constantly.

As Ritter explains, “Rather than starting from scratch every time you start the same application, AOT lets you feed back the previous optimal state so the JVM already knows what to expect.” This innovation helps Java stay competitive in modern cloud-native environments where startup time and scalability are crucial.

Ritter also touches on Project Amber, which continues to bring gradual but meaningful improvements to the Java language, including enhancements to pattern matching. These refinements not only simplify code but also improve developer productivity—making the platform more approachable without sacrificing its maturity and power.

Combined, these updates position JDK 25 as one of the most performance-focused releases in recent years. It reinforces Java’s strength as a reliable, efficient, and evolving language that continues to meet the demands of enterprise systems and cloud-native workloads alike.