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CharlesWiltgen
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build-performance

Diagnose and optimize slow Xcode builds by analyzing Build Timeline bottlenecks and inefficiencies.

1.1k|81|Updated Nov 30, 2025
Search Tags:#ci/cd#performance#optimization#build#swift#xcode#compilation
One-click install
npx skills add https://github.com/CharlesWiltgen/Axiom --skill build-performance
Or copy as Structured Prompt for Agent▼
Please help me install this Agent Skill.
Skill: build-performance
Source: https://github.com/CharlesWiltgen/Axiom/tree/main/plugins/axiom/skills/build-performance
Command: npx skills add https://github.com/CharlesWiltgen/Axiom --skill build-performance

SYSTEM DOCUMENTATION & REQUIREMENTS

💡 This Skill includes references (resource) components.

What problem does it solve?

This Skill addresses the common frustration of slow Xcode build times, which significantly hinder developer productivity. It provides a systematic approach to analyze, identify, and optimize bottlenecks in compilation, linking, and script phases.

Core Features & Use Cases

  • Systematic Optimization Workflow: Guides through measuring baselines, analyzing the Xcode Build Timeline, and identifying critical path bottlenecks.
  • Targeted Optimization Patterns: Provides specific fixes for slow Swift type checking, inefficient build phase scripts, and suboptimal compilation mode settings.
  • Parallelization Strategies: Leverages Xcode's parallel build capabilities and dependency management to shorten the critical path and maximize core utilization.
  • Use Case: When your incremental debug builds are taking too long, use this skill to ensure "Build Active Architecture Only" is set to YES and "Compilation Mode" is "Incremental" for Debug configurations, drastically reducing build times.

Quick Start

To measure your clean build time, run time xcodebuild build -scheme YourScheme in your terminal, then record the total duration.

Frequently Asked Questions about build-performance

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

FAQPage Schema
How do I measure and diagnose slow Xcode build times?▼

Measure baseline build time by running `time xcodebuild build -scheme YourScheme`, then analyze the Xcode Build Timeline to identify which compilation, linking, or script phases consume the most time. This reveals the specific bottleneck slowing your debug builds.

What settings reduce Swift type-checking time in Xcode?▼

Enable "Build Active Architecture Only" for debug builds and set "Compilation Mode" to "Incremental" instead of Whole Module Optimization. These settings drastically cut type-checking overhead during iterative development on Apple platforms.

Can I optimize CI/CD build pipelines for iOS and macOS projects?▼

Yes. Analyze your Build Timeline to detect bottlenecks in type checking and build scripts, then apply caching, conditional script execution, and improved parallelization strategies. These techniques shorten critical path and maximize core utilization in CI/CD workflows.

How do incremental builds improve Xcode compilation performance?▼

Incremental builds recompile only changed files rather than the entire project, dramatically reducing compile time for debug configurations. Ensure "Compilation Mode" is set to "Incremental" and "Build Active Architecture Only" is enabled to maximize this benefit.

What build phase scripts slow down Xcode compilation?▼

Inefficient build phase scripts—those running unconditionally or performing unnecessary work—extend build duration. Identify slow scripts in the Build Timeline, then optimize through conditional execution, caching, and parallelization to reclaim build time.

Does this approach work with tvOS, watchOS, and iPadOS projects?▼

Yes. This optimization workflow applies to all Apple platforms—iOS, macOS, iPadOS, tvOS, and watchOS—using Xcode 14 or later. The same Build Timeline analysis and incremental-build tuning patterns work across the entire Apple ecosystem.

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