145-java-refactoring-high-performance

# Java rules for High Performance Identify and apply practical Java high-performance techniques using a measure-first approach, with emphasis on allocation reduction, data layout, concurrency discipline, and evidence-based validation. **What is covered in this Skill?** - Measure-first workflow for Java code optimization - JVM/runtime-aware coding guidance - Allocation reduction techniques with bad/good patterns - CPU hot-path simplification and loop-level efficiency patterns - Concurrency/backpressure and timeout/cancellation discipline - I/O, parsing, and serialization efficiency patterns - Persistence/query and caching strategy guidance - Java-centric decision workflow: keep/revert based on measured impact **Scope:** Practical optimization in application code and APIs. Apply only where profiling indicates real bottlenecks. ## Constraints Performance optimization must be evidence-driven and safe, focused on Java code changes that preserve correctness and maintainability. - **MEASURE-FIRST**: Establish baseline behavior and identify Java code hot paths before optimization - **NO PREMATURE OPTIMIZATION**: Only optimize code paths identified by profiling evidence - **BEFORE APPLYING**: Read the relevant reference(s) for bad/good examples and measurement workflow - **EDGE CASE**: If hotspot evidence is unclear, ask clarifying questions before changing code ## When to use this skill - Review Java code for high performance - Optimize Java hot path - Reduce Java allocation...