# optimizing-wpf-memory

> Covers WPF memory optimization including Freezable patterns, common memory leak causes, and diagnostic techniques. Use when experiencing memory growth, implementing resource caching, or debugging memory issues.

- Author: vincent
- Repository: christian289/dotnet-with-claudecode
- Version: 20260129011625
- Stars: 11
- Forks: 0
- Last Updated: 2026-02-07
- Source: https://github.com/christian289/dotnet-with-claudecode
- Web: https://mule.run/skillshub/@@christian289/dotnet-with-claudecode~optimizing-wpf-memory:20260129011625

---

---
name: optimizing-wpf-memory
description: Covers WPF memory optimization including Freezable patterns, common memory leak causes, and diagnostic techniques. Use when experiencing memory growth, implementing resource caching, or debugging memory issues.
---

# WPF Memory Optimization

## 1. Freezable Pattern

### Why Freeze?

| Benefit | Description |
|---------|-------------|
| Thread-safe | Can be used across threads |
| No change tracking | Reduces overhead |
| Renderer optimization | Better GPU utilization |

### Basic Usage
```csharp
// Always freeze static resources
var brush = new SolidColorBrush(Colors.Red);
brush.Freeze();

var pen = new Pen(Brushes.Black, 1);
pen.Freeze();
```

### XAML Freeze
```xml
<Window xmlns:po="http://schemas.microsoft.com/winfx/2006/xaml/presentation/options"
        mc:Ignorable="po">
    <Window.Resources>
        <SolidColorBrush x:Key="FrozenBrush" Color="Red" po:Freeze="True"/>
    </Window.Resources>
</Window>
```

### When Freeze Fails
```csharp
if (brush.CanFreeze)
    brush.Freeze();
else
    // Has bindings or animations - cannot freeze
```

### Modifying Frozen Objects
```csharp
var clone = frozenBrush.Clone(); // Creates unfrozen copy
clone.Color = Colors.Blue;
clone.Freeze(); // Freeze again if needed
```

## 2. Common Memory Leaks

### Event Handler Leaks
```csharp
// ❌ LEAK: Static event holds reference
SomeStaticClass.StaticEvent += OnEvent;

// ✅ FIX: Unsubscribe in Unloaded
Unloaded += (s, e) => SomeStaticClass.StaticEvent -= OnEvent;
```

### CompositionTarget.Rendering Leak
```csharp
// ❌ LEAK: Never unsubscribed
CompositionTarget.Rendering += OnRendering;

// ✅ FIX: Always unsubscribe
Loaded += (s, e) => CompositionTarget.Rendering += OnRendering;
Unloaded += (s, e) => CompositionTarget.Rendering -= OnRendering;
```

### Binding Without INotifyPropertyChanged
```csharp
// ❌ LEAK: PropertyDescriptor retained
public string Name { get; set; } // No INPC

// ✅ FIX: Implement INPC
public string Name
{
    get => _name;
    set { _name = value; OnPropertyChanged(); }
}
```

### DispatcherTimer Leak
```csharp
// ❌ LEAK: Timer keeps running
_timer = new DispatcherTimer();
_timer.Tick += OnTick;
_timer.Start();

// ✅ FIX: Stop and cleanup
Unloaded += (s, e) =>
{
    _timer.Stop();
    _timer.Tick -= OnTick;
};
```

### Image Resource Leak
```csharp
// ❌ LEAK: Stream kept open
var bitmap = new BitmapImage(new Uri(path));

// ✅ FIX: Load immediately and release stream
var bitmap = new BitmapImage();
bitmap.BeginInit();
bitmap.CacheOption = BitmapCacheOption.OnLoad;
bitmap.UriSource = new Uri(path);
bitmap.EndInit();
bitmap.Freeze();
```

## 3. Diagnostic Checklist

### Code Review Points

- [ ] All static event subscriptions have unsubscribe logic
- [ ] CompositionTarget.Rendering unsubscribed in Unloaded
- [ ] DispatcherTimer stopped in Unloaded
- [ ] ViewModels implement INotifyPropertyChanged
- [ ] Images use `BitmapCacheOption.OnLoad`
- [ ] Static resources are Frozen

### Diagnostic Tools

| Tool | Purpose |
|------|---------|
| VS Diagnostic Tools | Real-time memory snapshots |
| dotMemory | Detailed retention paths |
| PerfView | GC and allocation analysis |

### Memory Monitor
```csharp
public static class MemoryMonitor
{
    public static void LogMemory(string context)
    {
        GC.Collect();
        GC.WaitForPendingFinalizers();
        GC.Collect();

        var mem = GC.GetTotalMemory(true) / 1024.0 / 1024.0;
        Debug.WriteLine($"[{context}] Memory: {mem:F2} MB");
    }
}
```

## 4. Resource Factory Pattern
```csharp
public static class FrozenResources
{
    public static SolidColorBrush CreateBrush(Color color)
    {
        var brush = new SolidColorBrush(color);
        brush.Freeze();
        return brush;
    }

    public static Pen CreatePen(Color color, double thickness)
    {
        var pen = new Pen(CreateBrush(color), thickness);
        pen.Freeze();
        return pen;
    }
}
```