Run Into the New Year with Java’s Ahead-of-Time Cache Optimizations – Inside.java

JDK 24 and 25 introduced Ahead-of-Time (AOT) cache optimizations that improve Java application startup time and warm-up performance. The AOT cache stores pre-processed classes and method profiles, shifting work from runtime to a preparation phase. JDK 24 requires a three-step workflow (train, assemble, run), while JDK 25 simplifies this to two steps. Creating an effective AOT cache requires consistent training runs that mirror production behavior, matching JDK versions and hardware, and proper classpath configuration. The cache must be regenerated when code, libraries, or JDK versions change. Training runs should cover typical startup paths using integration tests or production-like workloads, avoiding unnecessary class loading to keep the cache minimal.