bench.cs

[DisassemblyDiagnoser(maxDepth: 4)]
    public class Bench5
    {
        public int[] array = null;
        public int size = 500_000;
        public int x = 10;
        public int y = 10;

        [GlobalSetup]
        public void Setup()
        {
            Random rnd = new Random();
            array = new int[100_000_000];
            for (int i = 0; i < array.Length; i++)
                array[i] = rnd.Next(0, 10);
        }

        [Benchmark]
        public void SlowLoop()
        {
            var a = array;
            for (int i = 0; i < 1000; i++)
                a[i] += i + x;
        }

        [Benchmark]
        public void FastLoop()
        {
            var a = array;
            for (int i = 0; i < 1000; i++)
                a[i] = a[i] + i + x;
        }
    }