spacetris/docs/PERFORMANCE_OPTIMIZATION.md

# Performance Optimization Recommendations

## Current Performance Analysis

### Memory Management
- **Good**: Proper RAII patterns, smart pointers
- **Improvement**: Object pooling for frequently created/destroyed objects

### Rendering Performance
- **Current**: SDL3 with immediate mode rendering
- **Optimization Opportunities**: Batch rendering, texture atlasing

### Game Logic Performance
- **Current**: Simple collision detection, adequate for Tetris
- **Good**: Efficient board representation using flat array

## Specific Optimizations

### 1. Object Pooling for Game Pieces

```cpp
// src/gameplay/PiecePool.h
class PiecePool {
private:
    std::vector<std::unique_ptr<Piece>> available;
    std::vector<std::unique_ptr<Piece>> inUse;
    
public:
    std::unique_ptr<Piece> acquire(PieceType type);
    void release(std::unique_ptr<Piece> piece);
    void preAllocate(size_t count);
};
```

### 2. Texture Atlas for UI Elements

```cpp
// src/graphics/TextureAtlas.h
class TextureAtlas {
private:
    SDL_Texture* atlasTexture;
    std::unordered_map<std::string, SDL_Rect> regions;
    
public:
    void loadAtlas(const std::string& atlasPath, const std::string& configPath);
    SDL_Rect getRegion(const std::string& name) const;
    SDL_Texture* getTexture() const { return atlasTexture; }
};
```

### 3. Batch Rendering System

```cpp
// src/graphics/BatchRenderer.h
class BatchRenderer {
private:
    struct RenderCommand {
        SDL_Texture* texture;
        SDL_Rect srcRect;
        SDL_Rect dstRect;
    };
    
    std::vector<RenderCommand> commands;
    
public:
    void addSprite(SDL_Texture* texture, const SDL_Rect& src, const SDL_Rect& dst);
    void flush();
    void clear();
};
```

### 4. Memory-Efficient Board Representation

```cpp
// Current: std::array<int, COLS*ROWS> board (40 integers = 160 bytes)
// Optimized: Bitset representation for filled/empty + color array for occupied cells

class OptimizedBoard {
private:
    std::bitset<COLS * ROWS> occupied;  // 25 bytes (200 bits)
    std::array<uint8_t, COLS * ROWS> colors;  // 200 bytes, but only for occupied cells
    
public:
    bool isOccupied(int x, int y) const;
    uint8_t getColor(int x, int y) const;
    void setCell(int x, int y, uint8_t color);
    void clearCell(int x, int y);
};
```

### 5. Cache-Friendly Data Structures

```cpp
// Group related data together for better cache locality
struct GameState {
    // Hot data (frequently accessed)
    std::array<uint8_t, COLS * ROWS> board;
    Piece currentPiece;
    int score;
    int level;
    int lines;
    
    // Cold data (less frequently accessed)
    std::vector<PieceType> bag;
    Piece holdPiece;
    bool gameOver;
    bool paused;
};
```

## Performance Measurement

### 1. Add Profiling Infrastructure

```cpp
// src/core/Profiler.h
class Profiler {
private:
    std::unordered_map<std::string, std::chrono::high_resolution_clock::time_point> startTimes;
    std::unordered_map<std::string, double> averageTimes;
    
public:
    void beginTimer(const std::string& name);
    void endTimer(const std::string& name);
    void printStats();
};

// Usage:
// profiler.beginTimer("GameLogic");
// game.update(deltaTime);
// profiler.endTimer("GameLogic");
```

### 2. Frame Rate Optimization

```cpp
// Target 60 FPS with consistent frame timing
class FrameRateManager {
private:
    std::chrono::high_resolution_clock::time_point lastFrame;
    double targetFrameTime = 1000.0 / 60.0; // 16.67ms
    
public:
    void beginFrame();
    void endFrame();
    double getDeltaTime() const;
    bool shouldSkipFrame() const;
};
```

## Expected Performance Gains

1. **Object Pooling**: 30-50% reduction in allocation overhead
2. **Texture Atlas**: 20-30% improvement in rendering performance
3. **Batch Rendering**: 40-60% reduction in draw calls
4. **Optimized Board**: 60% reduction in memory usage
5. **Cache Optimization**: 10-20% improvement in game logic performance

## Implementation Priority

1. **High Impact, Low Effort**: Profiling infrastructure, frame rate management
2. **Medium Impact, Medium Effort**: Object pooling, optimized board representation
3. **High Impact, High Effort**: Texture atlas, batch rendering system