unity-performance-optimization

name	unity-performance-optimization
description	Unity Performance Optimization

Unity Performance Optimization

Use this skill when profiling frame rate issues, reducing draw calls, optimizing memory usage, or addressing CPU/GPU bottlenecks in Unity.

Profiling Workflow

1. Identify the bottleneck — Is it CPU, GPU, or memory? Check Profiler.
2. Measure — Get a baseline number (ms per frame, draw calls, memory).
3. Optimize — Apply the appropriate technique.
4. Verify — Re-measure. Did it actually improve? By how much?
5. Repeat — Go back to step 1.

Frame budgets:

Target FPS	Budget per Frame
30 fps	33.3 ms
60 fps	16.6 ms
90 fps (VR)	11.1 ms
120 fps	8.3 ms

LOD Groups

Reduce polygon count for distant objects:

LOD 0: Full detail    — 0-20% screen height → 5000 tris
LOD 1: Medium detail  — 20-50% → 2000 tris
LOD 2: Low detail     — 50-80% → 500 tris
Culled                 — 80-100% → not rendered

Setup: Add LODGroup component, assign mesh renderers to each LOD level.

Cross-fade: Enable for smooth transitions (uses dithering). Small GPU cost but looks much better.

LOD Bias: Project Settings > Quality > LOD Bias. Higher = use higher LOD longer. 1.0 = default, 2.0 = double quality distance.

Occlusion Culling

Skip rendering objects hidden behind other objects.

1. Mark occluders (walls, buildings) as Occluder Static
2. Mark occludees (everything) as Occludee Static
3. Bake: Window > Rendering > Occlusion Culling > Bake
4. Tune cell size for accuracy vs bake time

When to use: Dense indoor environments, urban areas with buildings. Less useful for open worlds with few occluders.

Frustum culling is free and automatic — only objects in the camera's view are rendered. Occlusion culling is additional.

Texture Optimization

Platform	Recommended Format	Notes
Desktop	BC7 (quality) / DXT5 (performance)	BC7 is higher quality at same size
Mobile (Android)	ASTC 6x6 (quality) / ETC2 (compatibility)	ASTC preferred for modern devices
Mobile (iOS)	ASTC 6x6	Standard for iOS
WebGL	DXT5 / ETC2	DXT for desktop browsers, ETC2 for mobile

Texture Settings

• Max Size: Match actual usage. A texture shown as 256px on screen does not need 4096px.
• Mipmaps: Enable for 3D objects (reduces aliasing and improves cache performance). Disable for UI sprites.
• Read/Write Enabled: OFF unless you need CPU access. Doubles memory.
• Generate Mipmaps > Streaming: Enable for large worlds. Loads mip levels on demand.

Mesh Optimization

• Polygon budgets: Set per-project. e.g., hero character 10K-50K tris, environment props 100-2K tris
• Mesh Compression: Low/Medium/High in import settings. Reduces disk/download size.
• Read/Write Enabled: OFF unless modifying mesh at runtime. Halves mesh memory.
• Optimize Mesh Data: Enable in Player Settings. Strips unused vertex attributes.
• Vertex Compression: Enable in Player Settings. Uses half-precision where possible.

Quick Wins Checklist

• Disable Raycast Target on non-interactive UI elements
• Split canvases by update frequency
• Mark non-moving objects as Static
• Enable GPU Instancing on shared materials
• Use NonAlloc physics queries
• Cache GetComponent results
• Set appropriate texture Max Size
• Disable Read/Write on textures and meshes you don't modify at runtime
• Configure collision matrix to skip impossible layer pairs
• Enable Incremental GC
• Use object pooling for frequently spawned/despawned objects
• Disable mipmaps on UI textures
• Profile before optimizing — measure, don't guess

Topic Pages

• Batching and Draw Call Reduction
• Object Pooling
• Shader Optimization