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Tags: unity, performance, optimization, lod, occlusion-culling, object-pooling, draw-calls, batching, game-dev Last updated: 2026-06-27

Performance Optimization Cheatsheet

Quick Reference

LOD (Level of Detail)

LOD Group Setup

1. Add LOD Group component to mesh parent.
2. Define LOD levels (0 = full detail, 1/2/3 = reduced).
3. Assign lower-detail meshes per level.
4. Set transition percentages.

LODGroup lodGroup = GetComponent<LODGroup>();
LOD[] lods = lodGroup.GetLODs();
lods[0].screenRelativeTransitionHeight = 0.1f;
lodGroup.SetLODs(lods);

Occlusion Culling

Setup

1. Window → Rendering → Occlusion Culling.
2. Mark static objects as Occluder Static / Occludee Static.
3. Bake occlusion data.
4. Enable Occlusion Culling on Camera.

Key Settings

Manual Checks

if (Vector3.Distance(player.position, transform.position) > cullDistance)
    return;

if (!IsVisibleFrom(renderer, Camera.main))
    return;

Object Pooling

Basic Pool

public class ObjectPool<T> where T : Component {
    Queue<T> pool = new();
    T prefab;

    public ObjectPool(T prefab, int initialSize) {
        this.prefab = prefab;
        for (int i = 0; i < initialSize; i++) {
            T obj = GameObject.Instantiate(prefab);
            obj.gameObject.SetActive(false);
            pool.Enqueue(obj);
        }
    }

    public T Get(Vector3 pos, Quaternion rot) {
        T obj = pool.Count > 0 ? pool.Dequeue() :
            GameObject.Instantiate(prefab);
        obj.transform.SetPositionAndRotation(pos, rot);
        obj.gameObject.SetActive(true);
        return obj;
    }

    public void Return(T obj) {
        obj.gameObject.SetActive(false);
        pool.Enqueue(obj);
    }
}

Unity Built-In Pool (2021+)

using UnityEngine.Pool;

ObjectPool<Bullet> bulletPool = new(
    createFunc:  () => Instantiate(bulletPrefab),
    actionOnGet: (b) => b.gameObject.SetActive(true),
    actionOnRelease: (b) => b.gameObject.SetActive(false),
    actionOnDestroy: (b) => Destroy(b.gameObject),
    defaultCapacity: 20
);

Bullet b = bulletPool.Get();
bulletPool.Release(b);

Pooling Tips

• Pre-warm the pool during loading screen.
• Don’t pool unique objects (player, UI).
• Pool frequently created/destroyed objects: bullets, particles, enemies, VFX, sound sources.
• Return objects to pool after use, not destroy.

Draw Call Batching

Static Batching

• Mark objects as Static → Batching Static.
• Unity combines static meshes at build time.
• Pros: zero runtime cost. Cons: more memory, non-moving only.

Dynamic Batching

• Automatic for small meshes (<300 verts).
• Enabled in Player Settings → Dynamic Batching.
• Pros: works on moving objects. Cons: per-frame CPU cost, vertex limit.

GPU Instancing

• Draw many copies of same mesh in one draw call.
• Enable on material: Enable GPU Instancing.

Graphics.DrawMeshInstanced(mesh, 0, material, matrices, count);

SRP Batcher (URP/HDRP)

• Enabled by default in URP/HDRP.
• Batches by shader variant, not mesh.
• Requires compatible shaders (Shader Graph, Unity).
• Check in Frame Debugger: “SRP Batcher” entries.

Profiling

Tools

Key Metrics

Profiler.BeginSample("MyExpensiveCode");
// Code to profile
Profiler.EndSample();

Common Bottleneck Fixes