Mastering Memory Efficiency with Compact Object Headers in JDK 25

Tue, 10 Feb 2026 07:00:01 +0000

Compact Object Headers are introduced in JDK 25 through JEP 519, marking a significant step forward for memory optimization in the JVM. First introduced experimentally in JEP 450 with JDK 24, this feature, authored by Roman Kennke, reduces the per-object memory footprint without slowing down performance.

The payoff is especially clear in object-heavy workloads and memory-constrained environments, such as those found in containers and cloud-native deployments.

In JDK 25, Compact Object Headers graduate from experimental to standard. However, they’re not enabled by default. Developers must turn them on using JVM flags to see the benefits.

Compactobjectheaders on JAVAPRO International

Mastering Memory Efficiency with Compact Object Headers in JDK 25