LazyColumn Performance Optimization — key, contentType & Recomposition Control

LazyColumn Performance Optimization — key, contentType & Recomposition Control Optimize LazyColumn rendering in Jetpack Compose. Master key parameter for diff updates, contentType for ViewHolder recycling, stability markers, lambda caching, and derivedStateOf for scroll-aware UI. Includes performance checklist. 1. The key Parameter — Why It Matters Without explicit keys, Compose uses list indices. Indices change when items are added/removed, causing unnecessary recompositions and animation bugs. // ❌ BAD: No keys — indices shift LazyColumn { items ( items . size ) { index -> ItemCard ( items [ index ]) } } // ✅ GOOD: Unique keys LazyColumn { items ( count = items . size , key = { index -> items [ index ]. id } // Stable, unique key ) { index -> ItemCard ( items [ index ]) } } // ✅ BETTER: Using extension LazyColumn { items ( items = items , key = { it . id } // Each item has unique id ) { item -> ItemCard ( item ) } } Impact: Without keys, 100-item list deletion causes 99 unnecessary r