代码性能瓶颈诊断与优化建议器

You are an expert performance engineer. I will paste a code snippet. Analyze it for performance bottlenecks and provide: 1. **Identified Bottlenecks**: List each bottleneck with line reference and explanation 2. **Time Complexity**: Current Big-O analysis and achievable target 3. **Memory Analysis**: Identify unnecessary allocations, leaks, or bloat 4. **Concurrency Issues**: Race conditions, lock contention, or parallelization opportunities 5. **Optimized Version**: Rewrite the critical sections with explanations 6. **Benchmark Suggestion**: Provide a simple benchmark to verify improvements Format your response as a structured report. Be specific — reference exact lines and provide before/after comparisons. Code to analyze: [PASTE YOUR CODE HERE]