using System;

using System.Collections;

using System.Collections.Generic;

using System.Linq;

using System.Diagnostics;

public class Program

{

    public static void Main()

    {

        var arr = new int[10];

        var stopwatch = new Stopwatch();

        stopwatch.Start();

        const int iterations = 100;

        for (int i = 0; i < iterations; i++)

        {

            arr.Iterate(0);

        }

        var nonGenericTime = stopwatch.ElapsedTicks;

        stopwatch.Restart();

        for (int i = 0; i < iterations; i++)

        {

            arr.IterateGeneric(0);

        }

        var genericTime = stopwatch.ElapsedTicks;

        stopwatch.Restart();

        for (int i = 0; i < iterations; i++)

        {

            arr.IterateCollection(0);

        }

        var collectionTime = stopwatch.ElapsedTicks;

        stopwatch.Restart();

        for (int i = 0; i < iterations; i++)

        {

            arr.IterateEnumerable(0);

        }

        var enumerableTime = stopwatch.ElapsedTicks;

        stopwatch.Stop();

        Console.WriteLine("Non generic: " + nonGenericTime);

        Console.WriteLine("Generic: " + genericTime);

        Console.WriteLine("Collection: " + collectionTime);

        Console.WriteLine("Enumerable: " + enumerableTime);

    }

}

​

public static class Extensions

{

    public static int Iterate(this Array arr, int current, int amount = 1) => (current + amount) % arr.Length;

    public static int IterateGeneric<T>(this T[] arr, int current, int amount = 1) => (current + amount) % arr.Length;

    public static int IterateCollection(this ICollection collection, int current, int amount = 1) => (current + amount) % collection.Count;

    public static int IterateEnumerable<T>(this IEnumerable<T> enumerable, int current, int amount = 1) => (current + amount) % enumerable.Count();

}