SwiftUI Performance Audit

Attribution: copied from @Dimillian’s Dimillian/Skills (2025-12-31).

Overview

Audit SwiftUI view performance end-to-end, from instrumentation and baselining to root-cause analysis and concrete remediation steps.

Workflow Decision Tree

• If the user provides code, start with "Code-First Review."
• If the user only describes symptoms, ask for minimal code/context, then do "Code-First Review."
• If code review is inconclusive, go to "Guide the User to Profile" and ask for a trace or screenshots.

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 or resizing.
• Over-animated hierarchies (implicit animations on large trees).

Provide:

• Likely root causes with code references.
• Suggested fixes and refactors.
• If needed, a minimal repro or instrumentation suggestion.

2. Guide the User to Profile

Explain how to collect data with Instruments:

• Use the SwiftUI template in Instruments (Release build).
• Reproduce the exact interaction (scroll, navigation, animation).
• Capture SwiftUI timeline and Time Profiler.
• Export or screenshot the relevant lanes and the call tree.

Ask for:

• Trace export or screenshots of SwiftUI lanes + Time Profiler call tree.
• Device/OS/build configuration.

3. Analyze and Diagnose