Speed isn't just optimization — it's architecture. Here's how I restructured a Node.js API to consistently respond in under 100ms. First, connection pooling. A single PostgreSQL connection pool shared across workers eliminated the per-request connection overhead. Second, query batching using DataLoader reduced N+1 queries by 90%. Third, and most impactful: moving from synchronous middleware chains to a pre-computed handler pipeline. By resolving all middleware at startup, each request only executes the exact chain it needs.