geometry-tower-defense/.omc/skills/perf-profile/SKILL.md

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---
name: perf-profile
description: "Structured performance profiling workflow. Identifies bottlenecks, measures against budgets, and generates optimization recommendations with priority rankings."
argument-hint: "[system-name or 'full']"
user-invocable: true
agent: performance-analyst
allowed-tools: Read, Glob, Grep, Bash
---
## 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