Program.cs

public class Program
{
    static void Main(string[] args)
    {
        Console.WriteLine(Run());
        Console.ReadLine();
    }

    public static decimal Run()
    {
        decimal total = 0;

        TaxCalculator calculator = new TaxCalculator1();

        // Frequent calls to simulate performance hits
        for (var i = 0; i < 5_000_000; i++)
        {
            total += calculator.CalculateTaxes();
        }

        calculator = new TaxCalculator2();

        // Frequent calls to simulate performance hits
        for (var i = 0; i < 5_000_000; i++)
        {
            total += calculator.CalculateTaxes();
        }

        return total;
    }
}