static void Main(string[] args)
{
string test1 = "Hello World";
StringBuilder test2 = new StringBuilder("Hello World");


Console.WriteLine("Concatenating 'Hello World' 20000 times using String.");
Console.WriteLine("Start Time: " + DateTime.Now.ToString());
for (int x=0; x<= 20000; x++)
{
test1 += "Hello World";

}
Console.WriteLine("Finish Time: " + DateTime.Now.ToString());
Console.WriteLine();

Console.WriteLine("Concatenating 'Hello World' 20000 times using StringBuilder.");
Console.WriteLine("Start Time: " + DateTime.Now.ToString());
for (int x=0; x<= 20000; x++)
{
test2.Append("Hello World");

}
Console.WriteLine("Finish Time: " + DateTime.Now.ToString());
Console.ReadLine();
}