Performance Profiling

Guide performance profiling for Apple platform apps with Instruments, Xcode diagnostics, and MetricKit. Use when investigating app hangs, stutters, high CPU, memory leaks, memory growth, OOM crashes, slow launch, battery drain, thermal issues, App Store performance readiness, or when adding os_signpost and measurement hooks.

Scenario: Plan an evidence-first investigation for an iOS app that stutters after several minutes.

Example input

# Symptoms

The timeline starts smoothly, then drops frames after editing for 8–10 minutes.
Memory grows continuously and does not fall after closing the editor.

Expected output

# Profiling plan

1. Record a reproducible signposted editing session.
2. Capture Time Profiler and Allocations traces.
3. Compare live-object growth before and after closing the editor.
4. Inspect retain cycles with Memory Graph.
5. Re-run the same scenario after the narrow fix.