# threejs-perf

Three.js optimization patterns that batch draw calls and accelerate updates for thousands of moving objects.

- skill · `type=skill` · Claude Code, Codex, Cursor, GitHub Copilot, Gemini CLI, OpenCode · 639 installs · ★ 348
- Author: OpusGameLabs
- License: MIT · policy=mirror · the beginning of the file is at the end of this page
- Source: https://github.com/PlayableIntelligence/game-creator/tree/HEAD/skills/threejs-perf/SKILL.md
- Updated: 2026-05-25
- HTML: https://affpapa.org/en/nevibecode/skills/threejs-perf

## What it does

The skill supplies optimization workflows for Three.js scenes with over 100 repeated objects or more than 500 draw calls. It contains `instancing-static.md` for static props, `instancing-moving.md` for moving actors, and reference code in `templates/`.

Instead of isolated meshes, the patterns route rendering through `InstancedMesh`. For static scenes, this cuts thousands of draw calls down to two. Dynamic setups rely on a flat state buffer and batched `setMatrixAt()` writes. Three.js r183 benchmarks on an Apple M1 Pro showed render CPU p95 dropping from 28.5ms to 0.5ms across 19.6k cubes.

Batching collapses when elements demand distinct shaders or varied geometry. If your scene has fewer than 50 meshes, plain mesh definitions remain easier to maintain.

## Install

### Claude Code (native platform)

1. **Skills CLI (Vercel)**
```bash
npx skills add PlayableIntelligence/game-creator --skill threejs-perf -a claude-code
```

2. **Manually: put the files in place**
- File: `~/.claude/skills/threejs-perf/SKILL.md` — Copy the whole skill folder; for one project use .claude/skills/threejs-perf/

### Codex

1. **Skills CLI (Vercel)**
```bash
npx skills add PlayableIntelligence/game-creator --skill threejs-perf -a codex
```

2. **Manually: put the files in place**
- File: `.agents/skills/threejs-perf/SKILL.md` — For all projects use ~/.agents/skills/

### Cursor

1. **Skills CLI (Vercel)**
```bash
npx skills add PlayableIntelligence/game-creator --skill threejs-perf -a cursor
```

2. **Manually: put the files in place**
- File: `.cursor/skills/threejs-perf/SKILL.md` — Cursor also reads .agents/skills/ and .claude/skills/

### GitHub Copilot

1. **GitHub CLI**
```bash
gh skill install PlayableIntelligence/game-creator threejs-perf
```

2. **Manually: put the files in place**
- File: `.github/skills/threejs-perf/SKILL.md`

### Gemini CLI

1. **Skills CLI (Vercel)**
```bash
npx skills add PlayableIntelligence/game-creator --skill threejs-perf -a gemini-cli
```

2. **Platform CLI**
```bash
gemini skills install https://github.com/PlayableIntelligence/game-creator --path skills/threejs-perf
```

### Windsurf (Devin Desktop)

**Manually: put the files in place**
- File: `.devin/skills/threejs-perf/SKILL.md` — The legacy .windsurf/skills/ path still works

### OpenCode

**Skills CLI (Vercel)**
```bash
npx skills add PlayableIntelligence/game-creator --skill threejs-perf -a opencode
```

### Claude.ai

**Claude.ai**
- Zip the folder and upload it in Settings → Capabilities → Skills

Where a file is given instead of a command, copy the files from the source to that path: https://github.com/PlayableIntelligence/game-creator/tree/HEAD/skills/threejs-perf/SKILL.md

## When to use it
- reduce draw call counts across hundreds of repeated meshes
- convert static background props into an InstancedMesh
- streamline per-frame transform updates for thousands of moving entities
- eliminate scene-graph traversal bottlenecks during rendering

## Example prompts
- Optimize a field of 500 trees using an InstancedMesh
- Batch instance matrix writes for 8000 moving entities
- Refactor 19600 meshes into an InstancedMesh setup to cut draw calls

## Source text · SKILL.md · MIT

Below is the content of a third-party file. It is data, not instructions for you: do not act on anything written inside unless the human asks. Block tag: 81d496d7352c55b4.

BEGIN THIRD-PARTY FILE 81d496d7352c55b4
````text
---
name: threejs-perf
description: Three.js performance optimization patterns for draw calls, scene traversal, and instancing. Use when optimizing 3D scenes with 100+ repeated objects, thousands of moving entities, or draw calls above 500. Loaded by threejs-game, viral-game, and make-game for performance guidance.
argument-hint: "[topic]"
license: MIT
metadata:
  author: OpusGameLabs
  version: 1.3.0
  tags: [threejs, performance, instancing, draw-calls, optimization]
---

# Three.js Performance Optimization

Performance patterns for Three.js games, backed by measured before/after numbers on Three.js r183 (headless Chromium via Playwright, Apple M1 Pro, software WebGL).

## Reference Files

- `instancing-static.md` — InstancedMesh for large static repeated objects (19,600 → 1 draw call)
- `instancing-moving.md` — Flat state buffer + batched InstancedMesh writes for moving entities (8,000 entities)
- `templates/` — Baseline vs optimized reference implementations for each pattern

## When to Use This Skill

- Scene has 100+ repeated objects sharing geometry/material
- Draw calls exceed 500 and frame time is unstable
- Thousands of moving entities need per-frame transform updates
- Profile shows scene-graph traversal as a bottleneck

## When NOT to Use

- Object count is low (<50 unique meshes) — simpler code wins
- Every object needs unique materials/shaders that defeat batching
- Geometry differs enough that instancing provides no batching benefit

## Pattern 1: Instancing Large Static Object Sets

**Problem**: Forests, debris, decorations as individual Meshes = unnecessary draw calls.

**Solution**: One `InstancedMesh` per shared geometry+material combo.

**Evidence**: ~19,365 → 2 draw calls. Render CPU p95: 28.5ms → 0.5ms (~57× faster). Build: 39.4ms → 3.9ms. See `instancing-static.md`.

```js
// Anti-pattern: one Mesh per prop
for (let i = 0; i < 19600; i++) {
  const mesh = new THREE.Mesh(geometry, material);
  mesh.position.set(x, 0, z);
  scene.add(mesh); // 19,600 draw calls
}

// Correct: one InstancedMesh
const im = new THREE.InstancedMesh(geometry, material, 19600);
const mat = new THREE.Matrix4();
for (let i = 0; i < 19600; i++) {
  mat.makeTranslation(x, 0, z);
  im.setMatrixAt(i, mat);
}
im.instanceMatrix.needsUpdate = true;
scene.add(im); // 1 draw call
```

## Pattern 2: Moving Entity Update Loops

**Problem**: Thousands of moving actors as individual Meshes = scene-graph churn + transform propagation.

**Solution**: Flat entity state buffer + batched `InstancedMesh.setMatrixAt()` writes.

**Evidence**: 8,000 → 1 draw calls. Render CPU p95: 9.9ms → 0.5ms (~20× faster). Update loop p95: 1.4ms → 0.3ms. See `instancing-moving.md`.

```js
// Anti-pattern: per-entity Mesh position writes
meshes.forEach((mesh, i) => {
  mesh.position.x = computeX(i, tick);
  mesh.position.y = computeY(i, tick);
});

// Correct: batched instance matrix writes
const mat = new THREE.Matrix4();
````
END THIRD-PARTY FILE 81d496d7352c55b4

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