using System;

using System.Diagnostics;

​

public class Program

{

    public static void Main()

    {

        int i1 = 4;

        int i2 = 8;

        int i3 = 15;

        int i4 = 16;

        double d = 23.42d;

        var sw1 = Stopwatch.StartNew();

        for (int i = 0; i < 3000000; i++)

        {

            var s = $"{i1}, {i2}, {i3}, {i4}, {d}!";

        }

​

        sw1.Stop();

        var sw2 = Stopwatch.StartNew();

        for (int i = 0; i < 3000000; i++)

        {

            var s = $"{i1.ToString()}, {i2.ToString()}, {i3.ToString()}, {i4.ToString()}, {d.ToString()}!";

        }

​

        sw2.Stop();

        Console.WriteLine($"Not optimized: {sw1.Elapsed}; Optimized: {sw2.Elapsed}");

    }

}