StringBuilder vs. Concatenation

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Diagnostics;
 
namespace ConsoleApplication4
{
    class Program
    {
        static void Main(string[] args)
        {
            string[] words = ("Quisque in neque at orci congue " +
                            "tempor. Donec id eros velit, eu " +
                            "sodales est. Sed purus eros, tempor  " +
                            "id ultricies eget, volutpat a mauris.  " +
                            "Suspendisse potenti. Suspendisse id  " +
                            "ligula nec felis mattis pellentesque  " +
                            "nec quis ipsum. Vivamus sed metus nunc,  " +
                            "non eleifend ligula. Sed mollis sagittis  " +
                            "pellentesque. Nam sit amet ante ut risus  " +
                            "pulvinar rhoncus. Vestibulum molestie  " +
                            "feugiat leo sed placerat. Sed consectetur " +
                            "velit ut magna molestie molestie tincidunt " +
                            "magna viverra. Quisque eu diam lacus. Sed  " +
                            "blandit, felis vel sollicitudin pellentesque, " +
                            "sapien nisl ullamcorper mauris, dapibus  " +
                            "accumsan diam augue et diam. Ut suscipit  " +
                            "nibh pretium nisi pulvinar vitae condimentum  " +
                            "felis mattis. Donec justo orci, gravida in  " +
                            "aliquam et, cursus sit amet sapien. Pellentesque " +
                            "mauris ipsum, ornare ac blandit nec, pretium  " +
                            "nec purus. Curabitur malesuada, lectus at  " +
                            "fermentum tempus, risus orci condimentum  " +
                            "lorem, id consequat dolor velit sed arcu.  " +
                            "Duis hendrerit rutrum tellus, a dignissim  " +
                            "velit facilisis ac. Curabitur pretium quam a " +
                            "metus sagittis mattis. Cum sociis natoque  " +
                            "penatibus et magnis dis parturient montes,  " +
                            "nascetur ridiculus mus.").Split(" ".ToCharArray());
 
 
            TimeSpan concatenationTestTime = TestConcatenation(words);
            TimeSpan stringbuilderTestTime = TestStringBuilder(words);
 
            Console.WriteLine(string.Format("StringBuilder: {0}", stringbuilderTestTime));
            Console.WriteLine(string.Format("Concatenation: {0}", concatenationTestTime));
 
            Console.ReadLine();
 
        }
 
        static TimeSpan TestConcatenation(string[] words)
        {
            string finalResult = string.Empty;
            Stopwatch sw = new Stopwatch();
            sw.Start();
            for (int i = 0; i < 100; i++)
            {
                foreach (string word in words)
                {
                    finalResult = finalResult + word;
                    finalResult = finalResult + " ";
                }
            }
            sw.Stop();
            return sw.Elapsed;
        }
 
        static TimeSpan TestStringBuilder(string[] words)
        {
            string finalResult = string.Empty;
            StringBuilder full = new StringBuilder();
            Stopwatch sw = new Stopwatch();
            sw.Start();
            for (int i = 0; i < 100; i++)
            {
                foreach (string word in words)
                {
                    full.Append(word);
                    full.Append(" ");
                }
            }
            finalResult = full.ToString();
            sw.Stop();
            return sw.Elapsed;
        }
    }
}