Program.cs

using System.Runtime.CompilerServices;
using BenchmarkDotNet.Attributes;
using BenchmarkDotNet.Running;

namespace BenchmarkCore
{
    class Program
    {
        static void Main(string[] args)
        {
            BenchmarkRunner.Run<ArrayGet>();
        }
    }

    public class ArrayGet
    {
        public int[] ArrayInt;
        public StrongBox<int>[] ArrayObject;

        [Params(100, 1000, 10_000)]
        public int N;

        [GlobalSetup]
        public void Setup()
        {
            ArrayObject = new StrongBox<int>[N];
            for (int i = 0; i < N; i++) ArrayObject[i] = new StrongBox<int>(i);

            ArrayInt = new int[N];
            for (int i = 0; i < N; i++) ArrayInt[i] = i;
        }

        [Benchmark(Baseline = true)]
        public int Sum()
        {
            int sum = 0;

            for (int i = 0; i < N; i++)
                sum += ArrayInt[i];

            return sum;
        }

        [Benchmark]
        public int SumObject()
        {
            int sum = 0;

            for (int i = 0; i < N; i++)
                sum += ArrayObject[i].Value;

            return sum;
        }
    }
}