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