Optimizing Performance

This one walks you through the full performance optimization cycle: measure baseline, identify bottlenecks, apply fixes, measure again. It covers frontend stuff like bundle splitting and memoization, backend patterns like multi-layer caching and async job queues, plus database query optimization. The real value is in the structure. It forces you to profile before changing anything and gives you concrete metrics to hit (P95 under 500ms, LCP under 2.5s). Good for when something feels slow but you're not sure where to start digging. The comparison tables and checklist format keep you honest about whether your changes actually helped.