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]