swiftui-performance-auditlisted

# SwiftUI Performance Audit ## Overview Audit SwiftUI view performance from instrumentation and baselining to root-cause analysis and concrete remediation steps. ## Workflow Decision Tree 1. **If user provides code**: Start with Code-First Review 2. **If user only describes symptoms**: Ask for minimal code/context, then Code-First Review 3. **If code review is inconclusive**: Guide user to profile with Instruments ## 1. Code-First Review ### Collect - Target view/feature code - Data flow: state, environment, observable models - Symptoms and reproduction steps ### Focus On - View invalidation storms from broad state changes - Unstable identity in lists (`id` churn, `UUID()` per render) - Heavy work in `body` (formatting, sorting, image decoding) - Layout thrash (deep stacks, `GeometryReader`, preference chains) - Large images without downsampling - Over-animated hierarchies (implicit animations on large trees) - Non-lazy containers (`VStack`/`HStack`) holding large collections instead of `LazyVStack`/`LazyHStack` - Async work in `.task` without relying on its automatic cancellation when the view disappears - Closures that may run off the main thread (`Shape.path(in:)`, `visualEffect`, `Layout` protocol methods, `onGeometryChange`) touching `@MainActor` state directly instead of capturing values ### Provide - Likely root causes with code references - Suggested fixes and refactors - Minimal repro or instrumentation suggestion if needed ## 2. Guide User to Profile Befor