go-performance-review

# Go Performance Review ## Purpose Identify performance issues and resource inefficiency in Go code. This skill exists because performance findings are almost all Medium severity and get systematically crowded out when mixed with High-severity Security/Concurrency findings. Important distinction: **lock contention** is performance (here); **race condition** is concurrency (`go-concurrency-review`). This skill does NOT cover: security, concurrency correctness, code style, test quality, error handling, or business logic — those belong to sibling vertical skills. ## When To Use - Code contains `make([]T, ...)` or `make(map[K]V, ...)` - Code builds strings in loops - Code queries DB/Redis inside loops - Code configures connection pools or HTTP clients - Code runs on hot paths (per-request, high-frequency) ## When NOT To Use - Security vulnerabilities → `go-security-review` - Race conditions, goroutine leaks → `go-concurrency-review` - Code style/lint → `go-quality-review` - Error handling → `go-error-review` ## Mandatory Gates ### 1) Go Version Gate Read `go.mod`. Key: `strings.Clone` (1.20+), `slices.Clone` (1.21+). ### 2) Anti-Example Suppression Gate MUST quote specific evidence. Category match alone insufficient. Embedded anti-examples: - **"Should pre-allocate slice"** — when slice is small (<16 elements) or size is truly unknown at creation time. Must cite evidence the slice is large and size is known. - **"Should use sync.Pool"** — when object is small and alloca...