J2se 6 Update 14 -

: A new optimization ( -XX:+DoEscapeAnalysis ) allowed the compiler to determine if an object is "escaped" (used outside a method). If it isn't, the JVM can allocate the object on the stack instead of the heap, significantly speeding up execution and reducing garbage collection overhead.

: The -XX:+UseCompressedOops option was introduced to improve the performance of 64-bit JREs on heaps smaller than 32GB. It allows 64-bit JVMs to use 32-bit references, reducing memory footprint and improving cache efficiency. J2Se 6 Update 14

: Update 14 marked the first time the G1 collector was available to the public. It was designed to replace the Concurrent Mark-Sweep (CMS) collector, offering better predictability and reduced heap fragmentation through incremental compaction. : A new optimization ( -XX:+DoEscapeAnalysis ) allowed

Java SE 6 Update 14 Release Notes. - Oracle It allows 64-bit JVMs to use 32-bit references,

, released by Sun Microsystems on May 29, 2009, was a landmark update that introduced several highly anticipated performance features and significant JVM improvements. Key Highlights and Performance Features

Update 14 was essentially a "feature backport" release. By including G1 and compressed pointers, Sun gave developers a preview of the performance gains coming in Java 7 while maintaining the stable environment of Java 6.