perf-profile

---
name: perf-profile
description: Structured performance profiling workflow. Identifies bottlenecks, measures against budgets, and generates optimization recommendations with priority rankings.
license: MIT
---

## Phase 1: Determine Scope

Read the argument:

- System name → focus profiling on that specific system
- `full` → run a comprehensive profile across all systems

---

## Phase 2: Load Performance Budgets

Check for existing performance targets in design docs or CLAUDE.md:

- Target FPS (e.g., 60fps = 16.67ms frame budget)
- Memory budget (total and per-system)
- Load time targets
- Draw call budgets
- Network bandwidth limits (if multiplayer)

---

## Phase 3: Analyze Codebase

**CPU Profiling Targets:**
- `_process()` / `Update()` / `Tick()` functions — list all and estimate cost
- Nested loops over large collections
- String operations in hot paths
- Allocation patterns in per-frame code
- Unoptimized search/sort over game entities
- Expensive physics queries (raycasts, overlaps) every frame

**Memory Profiling Targets:**
- Large data structures and their growth patterns
- Texture/asset memory footprint estimates
- Object pool vs instantiate/destroy patterns
- Leaked references (objects that should be freed but aren't)
- Cache sizes and eviction policies

**Rendering Targets (if applicable):**
- Draw call estimates
- Overdraw from overlapping transparent objects
- Shader complexity
- Unoptimized particle systems
- Missing LODs or occlusion culling

**I/O Targets:**
- Save/load performance
- Asset loading patterns (sync vs async)
- Network message frequency and size

---

## Phase 4: Generate Profiling Report

```markdown
## Performance Profile: [System or Full]
Generated: [Date]

### Performance Budgets
| Metric | Budget | Estimated Current | Status |
|--------|--------|-------------------|--------|
| Frame time | [16.67ms] | [estimate] | [OK/WARNING/OVER] |
| Memory | [target] | [estimate] | [OK/WARNING/OVER] |
| Load time | [target] | [estimate] | [OK/WARNING/OVER] |
| Draw calls | [target] | [estimate] | [OK/WARNING/OVER] |

### Hotspots Identified
| # | Location | Issue | Estimated Impact | Fix Effort |
|---|----------|-------|------------------|------------|

### Optimization Recommendations (Priority Order)
1. **[Title]** — [Description]
   - Location: [file:line]
   - Expected gain: [estimate]
   - Risk: [Low/Med/High]
   - Approach: [How to implement]

### Quick Wins (< 1 hour each)
- [Simple optimization 1]

### Requires Investigation
- [Area that needs actual runtime profiling to confirm impact]
```

Output the report with a summary: top 3 hotspots, estimated headroom vs budget, and recommended next action.

---

## Phase 5: Scope and Timeline Decision

Activate this phase only if any hotspot has Fix Effort rated M or L.

Present significant-effort items and ask the user to choose for each:

- **A) Implement the optimization** (proceed with fix now or schedule it)
- **B) Reduce feature scope** (run `/scope-check [feature]` to analyze trade-offs)
- **C) Accept the performance hit and defer to Polish phase** (log as known issue)
- **D) Escalate to technical-director for an architectural decision** (run `/architecture-decision`)

If multiple items are deferred to Polish (choice C), record them under `### Deferred to Polish`.

This skill is read-only — no files are written. Verdict: **COMPLETE** — performance profile generated.

---

## Phase 6: Next Steps

- If bottlenecks require architectural change: run `/architecture-decision`.
- If scope reduction is needed: run `/scope-check [feature]`.
- To schedule optimizations: run `/sprint-plan update`.

### Rules
- Never optimize without measuring first — gut feelings about performance are unreliable
- Recommendations must include estimated impact — "make it faster" is not actionable
- Profile on target hardware, not just development machines
- Static analysis (this skill) identifies candidates; runtime profiling confirms