iOS Performance Router

You MUST use this skill for ANY performance issue including memory leaks, slow execution, battery drain, or profiling.

When to Use

Use this router when:

• App feels slow or laggy
• Memory usage grows over time
• Battery drains quickly
• Device gets hot during use
• High energy usage in Battery Settings
• Diagnosing performance with Instruments
• Memory leaks or retain cycles
• App crashes with memory warnings

Routing Logic

Memory Issues

Memory leaks (Swift) → /skill axiom-memory-debugging

• Systematic leak diagnosis
• 5 common leak patterns
• Instruments workflows
• deinit not called

Memory leaks (Objective-C blocks) → /skill axiom-objc-block-retain-cycles

• Block retain cycles
• Weak-strong pattern
• Network callback leaks

Performance Profiling

Performance profiling (GUI) → /skill axiom-performance-profiling

• Time Profiler (CPU)
• Allocations (memory growth)
• Core Data profiling (N+1 queries)
• Decision trees for tool selection

Automated profiling (CLI) → /skill axiom-xctrace-ref

• Headless xctrace profiling
• CI/CD integration patterns
• Command-line trace recording
• Programmatic trace analysis

Run automated profile → Use performance-profiler agent or /axiom:profile

• Records trace via xctrace
• Exports and analyzes data
• Reports findings with severity

Hang/Freeze Issues

App hangs or freezes → /skill axiom-hang-diagnostics

• UI unresponsive for >1 second
• Main thread blocked (busy or waiting)
• Decision tree: busy vs blocked diagnosis
• Time Profiler vs System Trace selection
• 8 common hang patterns with fixes
• Watchdog terminations

Energy Issues

Battery drain, high energy → /skill axiom-energy

• Power Profiler workflow
• Subsystem diagnosis (CPU/GPU/Network/Location/Display)
• Anti-pattern fixes
• Background execution optimization

Symptom-based diagnosis → /skill axiom-energy-diag

• "App at top of Battery Settings"
• "Device gets hot"
• "Background battery drain"
• Time-cost analysis for each path

API reference with code → /skill axiom-energy-ref

• Complete WWDC code examples
• Timer, network, location efficiency
• BGContinuedProcessingTask (iOS 26)
• MetricKit setup

MetricKit Integration

MetricKit API reference → /skill axiom-metrickit-ref

• MXMetricPayload parsing
• MXDiagnosticPayload (crashes, hangs)
• Field performance data collection
• Integration with crash reporting

Decision Tree

User reports performance issue
  ├─ Memory?
  │  ├─ Swift code? → memory-debugging
  │  └─ Objective-C blocks? → objc-block-retain-cycles
  │
  ├─ Hang/Freeze (UI unresponsive >1 second)?
  │  └─ YES → hang-diagnostics
  │
  ├─ Energy/Battery?
  │  ├─ Know the symptom? → energy-diag
  │  ├─ Need API reference? → energy-ref
  │  └─ General battery drain? → energy
  │
  ├─ MetricKit setup/parsing?
  │  └─ YES → metrickit-ref
  │
  ├─ Want to profile?
  │  ├─ GUI workflow? → performance-profiling
  │  ├─ CLI/automation? → xctrace-ref
  │  ├─ Run profile now? → performance-profiler agent
  │  └─ Unsure → performance-profiling
  │
  └─ General slow/lag? → performance-profiling

Critical Patterns

Memory Debugging (memory-debugging):

• 6 leak patterns: timers, observers, closures, delegates, view callbacks, PhotoKit
• Instruments workflows
• Leak vs caching distinction

Performance Profiling (performance-profiling):

• Time Profiler for CPU bottlenecks
• Allocations for memory growth
• Core Data SQL logging for N+1 queries
• Self Time vs Total Time

Energy Optimization (energy):

• Power Profiler subsystem diagnosis
• 8 anti-patterns: timers, polling, location, animations, background, network, GPU, disk
• Audit checklists by subsystem
• Pressure scenarios for deadline resistance

Example Invocations

User: "My app's memory usage keeps growing" → Invoke: /skill axiom-memory-debugging

User: "I have a memory leak but deinit isn't being called" → Invoke: /skill axiom-memory-debugging

User: "My app feels slow, where do I start?" → Invoke: /skill axiom-performance-profiling

User: "My Objective-C block callback is leaking" → Invoke: /skill axiom-objc-block-retain-cycles

User: "My app drains battery quickly" → Invoke: /skill axiom-energy

User: "Users say the device gets hot when using my app" → Invoke: /skill axiom-energy-diag

User: "What's the best way to implement location tracking efficiently?" → Invoke: /skill axiom-energy-ref

User: "Profile my app's CPU usage" → Use: performance-profiler agent (or /axiom:profile)

User: "How do I run xctrace from the command line?" → Invoke: /skill axiom-xctrace-ref

User: "I need headless profiling for CI/CD" → Invoke: /skill axiom-xctrace-ref

User: "My app hangs sometimes" → Invoke: /skill axiom-hang-diagnostics

User: "The UI freezes and becomes unresponsive" → Invoke: /skill axiom-hang-diagnostics

User: "Main thread is blocked, how do I diagnose?" → Invoke: /skill axiom-hang-diagnostics

User: "How do I set up MetricKit?" → Invoke: /skill axiom-metrickit-ref

User: "How do I parse MXMetricPayload?" → Invoke: /skill axiom-metrickit-ref