macrozheng

Oct 16, 2025 · Backend Development

How to Turn a 3‑Second Category Tree into 30 ms: A Real‑World Backend Optimization

This article analyzes a severe N+1 query performance disaster in a Java Spring Boot project, explains why the traditional recursive approach is slow, and presents a production‑tested solution that reduces database calls to one, uses O(n) tree construction, and adds multi‑level caching to achieve a 100‑fold speedup.