StringvsStringBuilder.cs

 class Program
    {
        const int limit = 300000;
        static void Main(string[] args)
        {
            var plusOperatorResult = WithPlusOperator();
            var stringBuildeResult = WithStringBuilder();

            Console.WriteLine("Plus Operator Result : " + plusOperatorResult);
            Console.WriteLine("String Builder Result : " + stringBuildeResult);

            Console.ReadLine();
        }

        static long WithPlusOperator()
        {
            string variable = "";
            Stopwatch watch = new Stopwatch();
            watch.Start();
            for (int i = 0; i < limit; i++)
            {
                variable += "x";
            }
            watch.Stop();
            return watch.ElapsedMilliseconds;
        }

        static long WithStringBuilder()
        {
            StringBuilder builder = new StringBuilder();
            Stopwatch watch = new Stopwatch();
            watch.Start();
            for (int i = 0; i < limit; i++)
            {
                builder.Append("x");
            }
            watch.Stop();
            return watch.ElapsedMilliseconds;
        }
    }