majiayu000 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
- Memory leak (Swift)? → memory-debugging
- Memory leak (Objective-C blocks)? → objc-block-retain-cycles
- App hang/freeze (UI unresponsive >1s)? → hang-diagnostics
- Battery drain (know the symptom)? → energy-diag
- Battery drain (need API reference)? → energy-ref
- Battery drain (general)? → energy
- MetricKit setup/parsing? → metrickit-ref
- Profile with GUI (Instruments)? → performance-profiling
- Profile with CLI (xctrace)? → xctrace-ref
- Run automated profile now? → performance-profiler agent
- General slow/lag? → performance-profiling
Anti-Rationalization
| Thought | Reality |
|---|---|
| "I know it's a memory leak, let me find it" | Memory leaks have 6 patterns. memory-debugging diagnoses the right one in 15 min vs 2 hours. |
| "I'll just run Time Profiler" | Wrong Instruments template wastes time. performance-profiling selects the right tool first. |
| "Battery drain is probably the network layer" | Energy issues span 8 subsystems. energy skill diagnoses the actual cause. |
| "App feels slow, I'll optimize later" | Performance issues compound. Profiling now saves exponentially more time later. |
| "It's just a UI freeze, probably a slow API call" | Freezes have busy vs blocked causes. hang-diagnostics has a decision tree for both. |
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