JDK 27 Cuts Object Header Overhead by 33% and Reduces CPU Usage by Up to 30%

JDK 27 introduces JEP 534, making compact object headers the default layout, shrinking the 12‑byte header to 8 bytes (a 33% reduction), which lowers heap memory consumption by over 20%, cuts CPU time by 8‑30% in benchmarks, reduces GC pressure, and requires no code changes.

Compact Object HeadersJDK 27JEP 534

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