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BMAD-METHOD/src/modules/bmgd/gametest/knowledge/performance-testing.md

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Performance Testing for Games

Overview

Performance testing ensures your game runs smoothly on target hardware. Frame rate, load times, and memory usage directly impact player experience.

Key Performance Metrics

Frame Rate

  • Target: 30fps, 60fps, 120fps depending on platform/genre
  • Measure: Average, minimum, 1% low, 0.1% low
  • Goal: Consistent frame times, no stutters

Frame Time Budget

At 60fps, you have 16.67ms per frame:

Rendering:     8ms  (48%)
Game Logic:    4ms  (24%)
Physics:       2ms  (12%)
Audio:         1ms  (6%)
UI:            1ms  (6%)
Headroom:      0.67ms (4%)

Memory

  • RAM: Total allocation, peak usage, fragmentation
  • VRAM: Texture memory, render targets, buffers
  • Goal: Stay within platform limits with headroom

Load Times

  • Initial Load: Time to main menu
  • Level Load: Time between scenes
  • Streaming: Asset loading during gameplay
  • Goal: Meet platform certification requirements

Profiling Tools by Engine

Unity

  • Profiler Window - CPU, GPU, memory, rendering
  • Frame Debugger - Draw call analysis
  • Memory Profiler - Heap snapshots
  • Profile Analyzer - Compare captures

Unreal Engine

  • Unreal Insights - Comprehensive profiling
  • Stat Commands - Runtime statistics
  • GPU Visualizer - GPU timing breakdown
  • Memory Report - Allocation tracking

Godot

  • Debugger - Built-in profiler
  • Monitors - Real-time metrics
  • Remote Debugger - Profile on device

Platform Tools

  • PIX (Xbox/Windows) - GPU debugging
  • RenderDoc - GPU capture and replay
  • Instruments (iOS/macOS) - Apple profiling
  • Android Profiler - Android Studio tools

Performance Testing Process

1. Establish Baselines

  • Profile on target hardware
  • Record key metrics
  • Create benchmark scenes

2. Set Budgets

  • Define frame time budgets per system
  • Set memory limits
  • Establish load time targets

3. Monitor Continuously

  • Integrate profiling in CI
  • Track metrics over time
  • Alert on regressions

4. Optimize When Needed

  • Profile before optimizing
  • Target biggest bottlenecks
  • Verify improvements

Common Performance Issues

CPU Bottlenecks

Issue Symptoms Solution
Too many game objects Slow update loop Object pooling, LOD
Expensive AI Spiky frame times Budget AI, spread over frames
Physics overload Physics spikes Simplify colliders, reduce bodies
GC stutter Regular hitches Avoid runtime allocations

GPU Bottlenecks

Issue Symptoms Solution
Overdraw Fill rate limited Occlusion culling, reduce layers
Too many draw calls CPU-GPU bound Batching, instancing, atlasing
Shader complexity Long GPU times Simplify shaders, LOD
Resolution too high Fill rate limited Dynamic resolution, FSR/DLSS

Memory Issues

Issue Symptoms Solution
Texture bloat High VRAM Compress, mipmap, stream
Leaks Growing memory Track allocations, fix leaks
Fragmentation OOM despite space Pool allocations, defrag

Benchmark Scenes

Create standardized test scenarios:

Stress Test Scene

  • Maximum entities on screen
  • Complex visual effects
  • Worst-case for performance

Typical Gameplay Scene

  • Representative of normal play
  • Average entity count
  • Baseline for comparison

Isolated System Tests

  • Combat only (no rendering)
  • Rendering only (no game logic)
  • AI only (pathfinding stress)

Automated Performance Testing

CI Integration

# Example: Fail build if frame time exceeds budget
performance_test:
  script:
    - run_benchmark --scene stress_test
    - check_metrics --max-frame-time 16.67ms --max-memory 2GB
  artifacts:
    - performance_report.json

Regression Detection

  • Compare against previous builds
  • Alert on significant changes (>10%)
  • Track trends over time

Platform-Specific Considerations

Console

  • Fixed hardware targets
  • Strict certification requirements
  • Thermal throttling concerns

PC

  • Wide hardware range
  • Scalable quality settings
  • Min/recommended specs

Mobile

  • Thermal throttling
  • Battery impact
  • Memory constraints
  • Background app pressure

Performance Testing Checklist

Before Release

  • Profiled on all target platforms
  • Frame rate targets met
  • No memory leaks
  • Load times acceptable
  • No GC stutters in gameplay
  • Thermal tests passed (mobile/console)
  • Certification requirements met

Ongoing

  • Performance tracked in CI
  • Regression alerts configured
  • Benchmark scenes maintained
  • Budgets documented and enforced