Performance Optimization

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Overview

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Performance Architecture

• GPU Instancing: Multiple fixtures share the same shader
• Custom Render Textures: Preprocessing DMX/AudioLink data once
• Shader-based Computation: No CPU overhead for lighting calculations
• Batching: Reduces draw calls dramatically
• No Real-time Unity Lights: Avoids expensive lighting calculations

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Performance Budget Guidelines

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Target Performance Metrics

• 90 FPS constant
• 50-100 VRSL fixtures
• High volumetric quality
• 3D noise enabled

• 72 FPS constant
• 100-150 VRSL fixtures
• Medium volumetric quality
• 2D noise only

• 60-90 FPS
• 150+ VRSL fixtures
• High quality settings

• 72 FPS constant
• 20-30 fixtures maximum
• Low volumetric quality
• Depth light disabled
• 3D noise disabled

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VRSL Control Panel Optimization

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Quality Modes

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Volumetric Quality

• Transparent rendering
• Full alpha blending
• Highest visual quality
• Most expensive (render queue 3002)

• Transparent rendering
• Optimized blending
• Good visual quality
• Moderate cost (render queue 3002)

• Alpha-to-coverage
• Opaque rendering
• Acceptable quality
• Lowest cost (render queue 2452)

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Projection Quality

• Transparent blending
• Smooth edges
• Render queue 3001

• Alpha-to-coverage
• Sharper edges
• Render queue 2451

• Blinder projections
• PAR projections
• Other projections

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Additional Quality Settings

• High: Transparent, smooth
• Low: Opaque, faster

• High: Full effects
• Low: Simplified

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Depth Light Toggle

• Enabled: Uses depth texture for volumetric lighting (better quality)
• Disabled: No depth dependency (Quest compatible, better performance)

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Volumetric Noise Toggle

• Creates realistic volumetric texture
• Expensive on GPU
• Can be disabled for major performance gain

• Fallback when 3D disabled
• Much cheaper
• Still acceptable quality

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Volumetric Mesh Quality

1. Open VRSL Control Panel
2. Navigate to volumetric mesh quality settings
3. Switch between mesh quality levels:
   • High: Full polygon count
   • Medium: Reduced polygon count
   • Low: Minimal polygon count
4. Apply globally to all fixtures in scene

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Fixture Optimization Strategies

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Fixture Count Guidelines

• Maximum 50 fixtures for best performance
• Can go higher with optimization
• Consider visual impact vs. count

• PC VR: 50-150 fixtures
• PC Desktop: 150-300 fixtures
• Quest: 20-30 fixtures maximum

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Component-Based Intensity Control

Fixture with all components: 3 draw calls
- Volumetric: 1 draw call
- Projection: 1 draw call  
- Fixture body: 1 draw call

Disable projection (set intensity to 0):
- Saves 1 draw call per fixture
- Saves fill rate on projection texture

1. Enable Component Mode on fixtures
2. Set unused component intensities to 0
3. Reduce draw calls significantly

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Fixture Placement

• Remove fixtures not visible to players
• Use stencil masks to hide lights in unused areas
• Consider player’s typical viewing angles
• Don’t place fixtures behind walls/ceilings

• Fewer, well-placed fixtures > many random ones
• Use wash lights for large areas
• Use spots for accents and focus
• Create depth with layers, not quantity

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Shader and Material Optimization

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GPU Instancing

• Fixtures with same material instance together
• Dramatically reduces draw calls
• Already optimized by VRSL

• Use VRSL’s material generation tool
• Don’t break prefab connections unnecessarily
• Keep materials shared where possible

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Custom Render Texture Settings

1. Select Control Panel in scene
2. Set _targetCRTUpdateRate to 0.0 (default)
3. For slower systems, can increase to 0.1 or higher

• Update Period controls refresh rate
• Lower = faster updates, more GPU load
• Higher = slower updates, less GPU load
• 0.0 = every frame (default)

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Material Property Blocks

• Maintains GPU instancing
• Efficient property updates
• Already optimized by VRSL scripts

• Modifying materials directly instead of using VRSL scripts
• Creating unique material instances per fixture
• Changing shared material properties

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Depth Light Optimization

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Adding Depth Light

1. In VRSL Control Panel, click “Spawn Depth Light”
2. Directional light with shadows appears
3. Position anywhere (direction matters, not position)
4. Adjust shadow settings:

Shadow Type: Soft Shadows
Strength: 1.0
Resolution: Medium or High
Bias: 0.05
Normal Bias: 0.4  
Near Plane: 0.2

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Quest Compatibility

1. Open VRSL Control Panel
2. Set RequireDepthLight = false
3. Either remove depth light or disable shadows
4. Reduces GPU load significantly

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DMX-Specific Optimization

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Interpolation Settings

1. Access via Control Panel > CRT Materials
2. Select Movement Interpolation material
3. Adjust smoothing:
   • Maximum smoothing (0): Best quality, most processing
   • Minimum smoothing (1): Fast movement, less processing

• VRSL automatically reduces interpolation in-game
• Configurable via inGameInterpolationModifier
• Default 1.55x reduction
• Improves performance without sacrificing quality

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Extended Universes

• More universes = larger textures = more VRAM
• Only enable if you need >512 channels
• Disable if using single universe for slight performance gain

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DMX Mode Selection

• Horizontal: Standard (recommended)
• Vertical: Equivalent to Horizontal
• Legacy: Slightly less efficient

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AudioLink Optimization

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AudioLink CRT

• Minimal overhead
• Shared across all AudioLink fixtures
• Pre-processes frequency data once

• Reduce AudioLink resolution if needed (in AudioLink prefab)
• Disable AudioLink when not playing music
• Use lower delay values (faster updates)

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Fixture Count

• No video decoding overhead
• Simpler data structure
• Can have 10-20% more fixtures vs. DMX

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Band Assignment

• Choose bands for artistic reasons
• All bands computed simultaneously

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Scene-Wide Optimization

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Occlusion Culling

1. Window > Rendering > Occlusion Culling
2. Bake occlusion data
3. VRSL fixtures will be culled when not visible
4. Major performance improvement in large venues

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LOD Groups

1. Create LOD groups on fixture prefabs
2. Add lower-poly versions at distances
3. Reduces vertex processing for distant fixtures

• LOD 0 (0-10m): Full detail
• LOD 1 (10-25m): 50% polygons
• LOD 2 (25m+): 25% polygons

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Stencil Masks

1. Spawn stencil masks from Control Panel:
   • Cube Mask
   • Cylinder Mask
   • Capsule Mask
   • Sphere Mask
2. Place in doorways, hallways, etc.
3. Lights won’t render through masks
4. Saves fill rate and processing

• Prevent light leaking between rooms
• Reduce overdraw in complex geometry
• Focus GPU power on visible areas

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Post-Processing Optimization

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Bloom Settings

Intensity: 0.3-0.5
Threshold: 0.9-1.1  
Soft Knee: 0.5
Clamp: 65472 (max HDR)
Diffusion: 7
Anamorphic Ratio: 0  
Color: White
Fast Mode: Enabled

• Enable Fast Mode
• Reduce Diffusion (number of passes)
• Increase Threshold (less pixels affected)
• Let users control via Local UI Panel

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Other Post-Processing

• Avoid: Screen Space Reflections (very expensive)
• Avoid: Ambient Occlusion (expensive)
• Use: Color Grading (cheap)
• Use: Vignette (cheap)
• Use: Bloom (moderate, optimized)

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Quest Optimization Checklist

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Monitoring Performance

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Unity Editor

• FPS: Target 90+ for VR, 60+ for desktop
• Batches: Lower is better (instancing helps)
• Tris: Monitor total triangles
• SetPass calls: Draw call overhead

1. Window > Analysis > Profiler
2. Enter Play Mode
3. Monitor:
   • GPU: Shader time, fill rate
   • Rendering: Draw calls, batches
   • Memory: Texture memory, mesh memory

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VRChat In-World

• Check your world’s performance rank
• Aim for “Good” or “Medium”
• “Very Poor” will limit audience

• Enable in VRChat settings
• Monitor during testing
• Test with multiple users

• Check before upload
• Review warnings and errors
• Address “Very Poor” ratings

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Optimization Workflow

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Common Performance Issues

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Low FPS with Few Fixtures

• Volumetric quality too high
• 3D noise enabled on many fixtures
• Depth shadows too high resolution
• Post-processing too aggressive
• Other scene elements (not VRSL)

• Lower volumetric quality to Medium or Low
• Disable 3D noise
• Reduce shadow resolution
• Optimize bloom settings

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High Draw Calls

• Too many unique materials
• Broken GPU instancing
• Too many different fixture types

• Use VRSL material generation tool
• Consolidate fixture types
• Ensure materials are shared
• Check instancing is working

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Memory Issues

• Too many high-res projection textures
• Large DMX render textures (9-universe mode)
• High-poly volumetric meshes

• Reduce projection texture resolution
• Disable extended universes if not needed
• Use lower-poly volumetric meshes
• Remove unused assets

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Best Practices Summary

• Profile early and often
• Optimize before adding more features
• Test in VRChat regularly (editor performance differs)
• Document what works for your hardware targets
• Plan for lowest common denominator

• High visual quality isn’t worth excluding users
• Medium quality VRSL still looks excellent
• Most users won’t notice optimizations
• Smooth frame rate > maximum quality
• Make quality adjustable for users

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Next Steps

• Set up DMX Control
• Configure AudioLink
• Learn about Video Streaming
• Create Custom Fixtures

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Resources

• Unity Optimization Manual
• VRChat World Optimization
• VRSL Discord - Performance help from community