# 🏎️ Performance Standards (The "Turbo" Protocol)

**Audience:** Linus Torvalds (The Kernel) & The Architect.
**Objective:** Speed is a Feature. Latency is a Bug.

> [!CRITICAL]
> **The Linus Mandate:**
> "I don't care if it's 'clean code'. If it takes 2 seconds to load a dropdown, it's garbage. Optimize it or delete it."

## 1. ⏱️ Latency Budgets (Hard Limits)

Every endpoint/function falls into a Tier:

*   **Tier 1 (Interactive):** `< 100ms` (UI interactions, Auto-complete).
*   **Tier 2 (Standard):** `< 500ms` (Form submissions, Page loads).
*   **Tier 3 (Batch):** `< 5s` (Reports, Complex calculations).
    *   *Rule:* If it takes > 5s, it MUST be Async (Background Job).

## 2. 🗄️ Database & IO (The N+1 Killer)

*   **No Loop Queries:** NEVER execute a SQL query inside a `for` loop.
    *   **❌ BAD:** `for user in users: db.get_profile(user.id)`
    *   **✅ GOOD:** `db.get_profiles(user_ids)` (Batch fetching).
*   **Select *:** Explicitly select columns. Do not drag 5MB of JSONB if you only need the `id`.

## 3. 💾 Memory & Resources

*   **Generators > Lists:** Use `yield` for processing large datasets. Do not load 1GB CSVs into RAM.
*   **Container Limits:** Respect the `512MB` limit set in `business_standards.md`.
    *   *Leak Detection:* If memory grows linearly over 1 hour, the container must be killed and investigated.

## 4. ⚡ Caching Strategy

*   **Read-Heavy Data:** Must be cached (Redis/Memcached) with a TTL.
*   **Cache Stampede:** Implement "Stale-While-Revalidate" patterns. Do not let 1000 users hit the DB simultaneously when cache expires.

## 5. 🐧 The Kernel's Optimization Checklist

Before merging, run the profiler:

- [ ] **Complexity:** Is this algorithm O(n) or O(n^2)? (Nested loops over large data = Reject).
- [ ] **IO:** Count the DB calls. Is it 1 or 100?
- [ ] **Payload:** Check the JSON response size. Is it > 100KB? (Gzip it or paginate it).
- [ ] **Async:** Are we blocking the Event Loop (Node/Python Asyncio) with CPU work?