ArrayVsListEnumeration.cs

using System.Collections.Generic;
using System.Linq;
using BenchmarkDotNet.Attributes;
using BenchmarkDotNet.Jobs;

[SimpleJob(RuntimeMoniker.NetCoreApp31)]
[SimpleJob(RuntimeMoniker.NetCoreApp50)]
public class ArrayVsListEnumeration
{
    private readonly List<LargeStruct> _largeStructsList = Enumerable.Range(1, 16).Select(i => new LargeStruct(i)).ToList();
    private readonly LargeStruct[] _largeStructArray = Enumerable.Range(1, 16).Select(i => new LargeStruct(i)).ToArray();

    private readonly List<SmallClass> _classList = Enumerable.Range(1, 16).Select(i => new SmallClass(i)).ToList();
    private readonly SmallClass[] _classArray = Enumerable.Range(1, 16).Select(i => new SmallClass(i)).ToArray();

    private readonly List<int> _intList = Enumerable.Range(1, 16).ToList();
    private readonly int[] _intArray = Enumerable.Range(1, 16).ToArray();

    [Benchmark]
    public int LargeStructList()
    {
        int counter = 0;
        foreach (var item in _largeStructsList)
        {
            counter += item.Index;
        }

        return counter;
    }

    [Benchmark]
    public int LargeStructArray()
    {
        int counter = 0;
        foreach (var item in _largeStructArray)
        {
            counter += item.Index;
        }

        return counter;
    }

    [Benchmark]
    public int ClassList()
    {
        int counter = 0;
        foreach (var item in _classList)
        {
            counter += item.Index;
        }

        return counter;
    }

    [Benchmark]
    public int ClassArray()
    {
        int counter = 0;
        foreach (var item in _classArray)
        {
            counter += item.Index;
        }

        return counter;
    }

    [Benchmark]
    public int IntList()
    {
        int counter = 0;
        foreach (var item in _intList)
        {
            counter += item;
        }

        return counter;
    }

    [Benchmark]
    public int IntArray()
    {
        int counter = 0;
        foreach (var item in _intArray)
        {
            counter += item;
        }

        return counter;
    }
}

public unsafe struct LargeStruct
{
    public int Index { get; }
    private fixed byte _array[60]; //Pad this struct to 64 bytes

    public LargeStruct(int index)
    {
        Index = index;
    }
}
public sealed class SmallClass
{
    public int Index { get; }

    public SmallClass(int index)
    {
        Index = index;
    }
}