refactor-performance

# Refactor Performance ## Trigger Use for clearly measurable performance bottlenecks. ## Inputs - Profile output, benchmark data, and affected files. ## Outputs - Performance-focused code changes plus evidence and fallback plan. ## Procedure 1. Identify measurable bottleneck and baseline metrics. 2. Implement minimal targeted optimization. 3. Add/retain benchmarks. 4. Confirm no regressions in existing correctness tests. ## Guardrails - Avoid speculative optimization. - Keep behavior intact. ## Success criteria - Measured improvement and all required tests passing. ## Prefer Superpowers - Use `verification-before-completion` for benchmark-based confidence checks. ## Avoid scope creep - Do not refactor unrelated call paths.