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swiftui-performance

Audit SwiftUI view performance and identify root causes of slow rendering.

Updated Mar 31, 2026
Search Tags:#performance#optimization#profiling#diagnostics#swiftui#instruments#code-review
One-click install
npx skills add https://github.com/DFly7/iOS-FastAPI-Supabase-AI --skill swiftui-performance-dfly7
Or copy as Structured Prompt for Agent▼
Please help me install this Agent Skill.
Skill: swiftui-performance
Source: https://github.com/DFly7/iOS-FastAPI-Supabase-AI/tree/main/.agents/skills/swiftui-performance
Command: npx skills add https://github.com/DFly7/iOS-FastAPI-Supabase-AI --skill swiftui-performance-dfly7

SYSTEM DOCUMENTATION & REQUIREMENTS

💡 This Skill includes references (resource) components.

What problem does it solve?

Diagnoses and resolves SwiftUI runtime performance issues such as slow rendering, janky scrolling, excessive body evaluations, identity churn, and main-thread work that causes hangs or frame drops. The Skill helps developers go from symptom to root cause using code review, Instruments guidance, and concrete remediation steps.

Core Features & Use Cases

  • Code-First Review: Identify costly patterns in view bodies, unstable identities in lists, and broad observable dependencies from a code sample.
  • Profiling Guidance: Step-by-step instructions for collecting and interpreting Instruments traces (SwiftUI lane, Time Profiler, Hangs) and Cause-and-Effect graphs.
  • Targeted Remediations: Practical fixes such as narrowing state scope, stabilizing ForEach ids, moving heavy work off the main thread, caching formatters, and downsampling images.
  • Verification: Advice for re-measuring improvements on Release builds and summarizing before/after metrics and expected effort.

Quick Start

Provide the slow SwiftUI view code, reproduction steps, device/build details, and an Instruments trace or screenshots for a focused performance audit.

Frequently Asked Questions about swiftui-performance

High-intent search queries and answers about installing and using this skill.

FAQPage Schema
Why does my SwiftUI view have slow rendering and janky scrolling?▼

Slow rendering and janky scrolling in SwiftUI are typically caused by excessive body evaluations, unstable ForEach identities, and expensive main-thread work. Code review and profiling pinpoint these root causes for targeted remediation.

How do I profile SwiftUI performance issues using Instruments?▼

Profiling SwiftUI performance with Instruments requires collecting and interpreting traces from the SwiftUI lane, Time Profiler, and Hangs instruments. Analyzing these traces reveals the exact sources of main-thread hangs and frame drops.

What is the best way to fix excessive view invalidation in SwiftUI?▼

Fixing excessive view invalidation involves narrowing state scope, stabilizing ForEach ids, and caching expensive objects like formatters. These remediations prevent unnecessary body recomputations and eliminate layout thrash.

Can I audit SwiftUI code without an Instruments trace?▼

Yes, a code-first review can identify costly patterns in view bodies, unstable list identities, and broad observable dependencies directly from source samples. Providing an Instruments trace simply enables deeper runtime analysis.

Does this approach work for high CPU usage from SwiftUI layout thrash?▼

Yes, diagnosing high CPU usage from layout thrash involves identifying broad observable dependencies and expensive body work. Remediations include moving heavy tasks off the main thread and downsampling images to reduce rendering overhead.

How do I verify SwiftUI performance improvements after remediation?▼

Verifying SwiftUI performance improvements requires re-measuring on Release builds after applying fixes. Summarizing before and after metrics confirms the reduction in frame drops and evaluates the development effort invested.

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