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