Performance Optimizer

This walks you through the measure-optimize-verify cycle for fixing slow code. It covers the usual suspects: N+1 queries, missing indexes, bloated payloads, unnecessary re-renders, and algorithmic inefficiency. The examples are concrete, like adding database indexes or switching from sequential to parallel API calls with Promise.all. What's useful here is the emphasis on measuring before and after with actual timing code, not just guessing at what's slow. It includes quick wins like enabling gzip and adding caching, plus a checklist to make sure you don't break things while speeding them up. Good for when users complain about lag or you're staring at a slow query log.