swift-performance

Start by running Instruments to identify bottlenecks in memory allocations and CPU usage. This Skill guides you through interpreting profiler output and applying language-level optimizations—like reducing ARC overhead, specializing generics, and optimizing collections—targeted at your hotspots rather than guessing where to optimize.

ARC (Automatic Reference Counting) manages object lifetime but incurs retain/release overhead. Understanding ARC behavior helps you avoid unnecessary reference cycles, reduce copy operations on value types, and apply copy-on-write patterns to minimize allocations in performance-critical code paths.

Value semantics determine how Swift manages data on the stack versus heap; poor layout choices trigger excessive allocations. This Skill teaches you to leverage value types strategically, understand struct and enum memory layout, and apply specialization techniques to write memory-efficient code for iOS and macOS.

Yes. Profiling-driven optimization focuses on hot paths where collection usage matters most. This Skill shows you how to select appropriate collection types, apply generics specialization, and use copy-on-write patterns to reduce overhead while keeping your existing architecture intact.

This Skill requires Swift 6.2+, Xcode 16+, and iOS 18+ or macOS 15+ to access features like InlineArray, Span, and @concurrent attributes. These additions provide new tools for performance tuning; earlier versions work for core optimization principles but lack these language-level capabilities.

This Skill provides patterns and benchmarks to guide code reviews, helping you recognize common memory and ARC pitfalls, unnecessary copies, and missed specialization opportunities. Use these patterns as a checklist during reviews to catch performance issues before they reach production.