axiom-performance

What the source does

• FilesystemNone observedNo reads or writes in the source
• NetworkNone observedNo outbound calls in the source
• ShellNone observedNo commands run in the source
• DependenciesPinnedNothing floats
• SecretsNone foundNo keys in source

Five audit layers

Gates applied: instruction override, no behavioural pass.

// Device settings: Developer Mode enabled, Xcode attached

2. **Device support**: Physical device profiling requires Developer Mode enabled

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| **Customization** | Full access to raw data | Predefined views |

Audit 0.4.1 · source sha 0f9ca4f3815b · 31 Oct 2026Report an issue or request a re-scan

• Publishercharleswiltgen GitHub userOwner of the repository this skill is read from
• Source foldercharleswiltgen/axiom/axiom-codex/skills/axiom-performanceThe exact folder we audited
• LicenceMITAs the repository states it
• Commit pinned for this verdict0f9ca4f3815bA new audit runs when the source changes
• Repository statusNot archivedPushed today
• Sandboxed runNot runSkills are read, not executed; layer L4 is skipped

Its description: Use when an Apple-platform app feels slow, memory grows, battery drains, or ANY performance issue needs diagnosing. Covers memory leaks, profiling, Instruments workflows, retain cycles, optimization.

---
name: axiom-performance
description: Use when an Apple-platform app feels slow, memory grows, battery drains, or ANY performance issue needs diagnosing. Covers memory leaks, profiling, Instruments workflows, retain cycles, optimization.
license: MIT
---

# Performance

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

**Bundled tools on Claude Code:** if `command -v <tool>` finds nothing (hooks off or `--bare`), use `<plugin-root>/tools/<tool>` in place of the bare name; `<plugin-root>` is two levels above this skill's `Base directory for this skill:` path.

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> **Auditors are skills here.** Where this router says "Launch `some-auditor` agent", invoke the
> matching Codex skill instead — same procedure, no Claude Code agent required.
>
> Available: `axiom-analyze-swift-performance`, `axiom-audit-energy`, `axiom-audit-memory`.
>
> The ones that shell out — builds, tests, simulators, crash symbolication — need shell access to run.
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## 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)** → See skills/memory-debugging.md
- Systematic leak diagnosis
- 5 common leak patterns
- Instruments workflows
- deinit not called

**Memory leak scan** → `axiom-audit-memory` (5-phase semantic audit: maps resource ownership, detects 6 leak patterns, reasons about missing cleanup, correlates compound risks, scores lifecycle health)

**Memory leaks (Objective-C blocks)** → See skills/objc-block-retain-cycles.md
- Block retain cycles
- Weak-strong pattern
- Network callback leaks

### Performance Profiling

**Performance profiling (GUI)** → See skills/performance-profiling.md
- Time Profiler (CPU), incl. Top Functions mode for scattered overhead (`OS27`)
- Allocations (memory growth)
- Core Data profiling (N+1 queries)
- Decision trees for tool selection
- Instruments 27 Run Comparisons, Swift executors instrument, Foundation Models instrument; Xcode 27 Organizer (Storage/hitches metrics, Metric Goals, Generate Recommendations)

**Automated profiling (CLI)** → See skills/xctrace-ref.md
- Headless xctrace profiling
- CI/CD integration patterns
- Command-line trace recording
- Programmatic trace analysis

**Run automated profile** → Use `performance-profiler` agent or `axiom-profile-performance`
- Records trace via xctrace
- Exports and analyzes data
- Reports findings with severity

**Compare two traces / detect regressions** → See skills/trace-comparison.md or `/axiom:compare-traces` (Claude Code only)
- Did this change slow down a hot path? Function-level CPU-share deltas
- CI gating with `xcprof compare --fail-on-regression` (non-zero exit)
- Regressions vs improvements, severity ranking, exit-code semantics

### Hang/Freeze Issues

**App hangs or freezes** → See skills/hang-diagnostics.md
- 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

**Corpus/aggregate hang triage (Sentry, ASC)** → `axiom-shipping (skills/production-triage.md)` + `triage-analyzer` agent
- Multiple grouped hang reports from an aggregator, not a single .ips file
- Classify `anr_idle_runloop` vs `anr_main_thread_block` across the corpus
- Flag suspension/idle-runloop false-positives (the #1 hang by user count is often noise)
- Cluster into root-cause families and rank by impact

### App Launch

**Slow app launch** → See skills/app-launch.md
- Slow first frame, frozen first screen, launch regression in Organizer
- Launch-phase model (pre-main / main→first frame / extended launch)
- Cold vs warm vs hot/resume vs notification launch — how to reproduce each
- App Launch instrument workflow, `dyld Activity`, measurement hygiene
- Pre-main fixes: linkage strategy (static vs dynamic vs mergeable, `MERGED_BINARY_TYPE`/`MERGEABLE_LIBRARY`), `+load`, main-thread deferral, priority inversion
- `XCTApplicationLaunchMetric` regression test, `MXAppLaunchMetric` field histograms, custom "app is interactive" signpost
- Push-notification launch path (tap→first pixel / tap→interactive targets)

### Energy Issues

**Battery drain, high energy** → See skills/energy.md
- Power Profiler workflow
- Subsystem diagnosis (CPU/GPU/Network/Location/Display)
- Anti-pattern fixes
- Background execution optimization

**Symptom-based diagnosis** → See skills/energy-diag.md
- "App at top of Battery Settings"
- "Device gets hot"
- "Background battery drain"
- Time-cost analysis for each path

**API reference with code** → See skills/energy-ref.md
- Complete WWDC code examples
- Timer, network, location efficiency
- BGContinuedProcessingTask (iOS 26)
- MetricKit setup

**Energy scan** → `axiom-audit-energy` (8 anti-patterns: timer abuse, polling, continuous location, animation leaks, background mode misuse, network inefficiency, GPU waste, disk I/O)

### Timer Safety

**Timer crash patterns (DispatchSourceTimer)** → See `axiom-integration` (skills/timer-patterns.md)
- 4 crash scenarios trapping with `BUG IN CLIENT OF LIBDISPATCH` — EXC_BREAKPOINT (SIGTRAP) on arm64, EXC_BAD_INSTRUCTION on Intel
- RunLoop mode gotcha (Timer stops during scroll)
- SafeDispatchTimer wrapper
- Timer vs DispatchSourceTimer decision

**Timer API reference** → See `axiom-integration` (skills/timer-patterns-ref.md)
- Timer, DispatchSourceTimer, Combine, AsyncTimerSequence APIs
- Lifecycle diagrams
- Platform availability

### Swift Performance

**Swift performance optimization** → See skills/swift-performance.md
- Value vs ref

Excerpt, first 6,000 characters of SKILL.md, verbatim from the audited commit. It is text from someone else’s repository, quoted so you can judge it before your agent reads it.

1. 2026-10-31
   ✕BLOCK D 69 / 100

   first audit · source 0f9ca4f3815b

Questions about axiom-performance

• github.com/charleswiltgen/axiom/tree/main/axiom-codex/skills/axi — the audited source at commit 0f9ca4f3815b and every finding aboveObserved · 31 Oct 2026

Spotted something wrong? Report a correction · Methodology