PropertyChangedArgBenchmarks.cs

using System.ComponentModel;
using System.Linq;
using BenchmarkDotNet.Attributes;
using BenchmarkDotNet.Attributes.Exporters;
using BenchmarkDotNet.Running;

[MemoryDiagnoser]
[MarkdownExporter]
public class PropertyChangedArgBenchmarks
{
    private NormalClass[] normal;
    private CachedClass[] cached;

    [Setup]
    public void SetupData()
    {
        normal = Enumerable.Range(0, ModelCount).Select(i => new NormalClass()).ToArray();
        foreach (var item in normal)
            item.PropertyChanged += EmptyHandler;
        cached = Enumerable.Range(0, ModelCount).Select(i => new CachedClass()).ToArray();
        foreach (var item in cached)
            item.PropertyChanged += EmptyHandler;
    }

    [Params(10, 100, 1000)]
    public int ModelCount { get; set; }

    [Params(10, 100, 1000, 5000)]
    public int ChangeCount { get; set; }

    [Benchmark]
    public void Normal()
    {
        for (int i = 0; i < ChangeCount; i++)
            for (int j = 0; j < ModelCount; j++)
                normal[j].Name = $"Normal {i}";
    }

    [Benchmark]
    public void Cached()
    {
        for (int i = 0; i < ChangeCount; i++)
            for (int j = 0; j < ModelCount; j++)
                cached[j].Name = $"Cached {i}";
    }

    private void EmptyHandler(object sender, PropertyChangedEventArgs args)
    {
    }
}

public class BaseClass : INotifyPropertyChanged
{
    public event PropertyChangedEventHandler PropertyChanged;

    protected void OnPropertyChanged(PropertyChangedEventArgs args)
    {
        PropertyChanged?.Invoke(this, args);
    }
}

public class NormalClass : BaseClass
{
    string name;

    public string Name
    {
        get => name;
        set
        {
            if (name == value)
                return;
            name = value;
            OnPropertyChanged(new PropertyChangedEventArgs(nameof(Name)));
        }
    }
}

public class CachedClass : BaseClass
{
    static PropertyChangedEventArgs nameArg = new PropertyChangedEventArgs(nameof(Name));

    string name;

    public string Name
    {
        get => name;
        set
        {
            if (name == value)
                return;
            name = value;
            OnPropertyChanged(nameArg);
        }
    }
}

public class Program
{
    public static void Main(string[] args)
    {
        BenchmarkRunner.Run<PropertyChangedArgBenchmarks>();
    }
}