C# String output: format or concat?

var p = new { FirstName = "Bill", LastName = "Gates" };

        Console.WriteLine("{0} {1}", p.FirstName, p.LastName);

        Console.WriteLine(p.FirstName + " " + p.LastName);

string.Format

string.Format

Bill Gates
Console.WriteLine(p.FirstName + " " + p.LastName); took: 8ms - 30488 ticks
Bill Gates
Console.WriteLine("{0} {1}", p.FirstName, p.LastName); took: 0ms - 182 ticks

Bill Gates
Console.WriteLine(FirstName + " " + LastName); took: 5ms - 20335 ticks
Bill Gates
Console.WriteLine(FirstName + " " + LastName); took: 0ms - 156 ticks
Bill Gates
Console.WriteLine(FirstName + " " + LastName); took: 0ms - 122 ticks
Bill Gates
Console.WriteLine("{0} {1}", FirstName, LastName); took: 0ms - 181 ticks
Bill Gates
Console.WriteLine("{0} {1}", FirstName, LastName); took: 0ms - 122 ticks
Bill Gates
String.Concat(FirstName, " ", LastName); took: 0ms - 142 ticks
Bill Gates
String.Concat(FirstName, " ", LastName); took: 0ms - 117 ticks

Console.WriteLine("{0} {1}", p.FirstName, p.LastName); took (avg): 0ms - 689 ticks
Console.WriteLine(p.FirstName + " " + p.LastName); took (avg): 0ms - 683 ticks

Stopwatch s = new Stopwatch();

        var p = new { FirstName = "Bill", LastName = "Gates" };

        //First print to remove the initial cost
        Console.WriteLine(p.FirstName + " " + p.LastName);
        Console.WriteLine("{0} {1}", p.FirstName, p.LastName);

        int n = 100000;
        long fElapsedMilliseconds = 0, fElapsedTicks = 0, cElapsedMilliseconds = 0, cElapsedTicks = 0;

        for (var i = 0; i < n; i++)
        {
            s.Start();
            Console.WriteLine(p.FirstName + " " + p.LastName);
            s.Stop();
            cElapsedMilliseconds += s.ElapsedMilliseconds;
            cElapsedTicks += s.ElapsedTicks;
            s.Reset();
            s.Start();
            Console.WriteLine("{0} {1}", p.FirstName, p.LastName);
            s.Stop();
            fElapsedMilliseconds += s.ElapsedMilliseconds;
            fElapsedTicks += s.ElapsedTicks;
            s.Reset();
        }

        Console.Clear();

        Console.WriteLine("Console.WriteLine("{0} {1}", p.FirstName, p.LastName); took (avg): " + (fElapsedMilliseconds / n) + "ms - " + (fElapsedTicks / n) + " ticks");
        Console.WriteLine("Console.WriteLine(p.FirstName + " " + p.LastName); took (avg): " + (cElapsedMilliseconds / n) + "ms - " + (cElapsedTicks / n) + " ticks");

string str = "{0} {1} is my friend. {3}, {2} is my boss.".FormatWith(prop1,prop2,prop3,prop4);

string name = String.Format(ApplicationStrings.General.InformalUserNameFormat,this.FirstName,this.LastName);

System.Diagnostics.Stopwatch s = new System.Diagnostics.Stopwatch();

    var p = new { FirstName = "Bill", LastName = "Gates" };

    s.Start();
    Console.WriteLine("{0} {1}", p.FirstName, p.LastName);
    s.Stop();
    Console.WriteLine("Console.WriteLine("{0} {1}", p.FirstName, p.LastName); took: " + s.ElapsedMilliseconds + "ms - " + s.ElapsedTicks + " ticks");

    s.Reset();
    s.Start();
    Console.WriteLine(p.FirstName + " " + p.LastName);
    s.Stop();

    Console.WriteLine("Console.WriteLine(p.FirstName + " " + p.LastName); took: " + s.ElapsedMilliseconds + "ms - " + s.ElapsedTicks + " ticks");

Bill Gates
Console.WriteLine("{0} {1}", p.FirstName, p.LastName); took: 2ms - 7280 ticks
Bill Gates
Console.WriteLine(p.FirstName + " " + p.LastName); took: 0ms - 67 ticks

Console.WriteLine("User {0} accessed {1} on {2}.", user.Name, fileName, timestamp);
vs
Console.WriteLine("User " + user.Name + " accessed " + fileName + " on " + timestamp + ".");

s.Start();
        for (var i = 0; i < n; i++)
            result = string.Concat(p.FirstName, " ", p.LastName);
        s.Stop();
        ceElapsedMilliseconds = s.ElapsedMilliseconds;
        ceElapsedTicks = s.ElapsedTicks;
        s.Reset();

1000000 x result = string.Format("{0} {1}", p.FirstName, p.LastName); took: 249ms - 3571621 ticks
1000000 x result = (p.FirstName + " " + p.LastName); took: 65ms - 944948 ticks
1000000 x result = string.Concat(p.FirstName, " ", p.LastName); took: 54ms - 780524 ticks

Console.WriteLine(String.Concat(p.FirstName," ",p.LastName));

class Program {
   static void Main(string[] args) {

      var p = new { FirstName = "Bill", LastName = "Gates" };

      var tests = new[] {
         new { Name = "Concat", Action = new Action(delegate() { string x = p.FirstName + " " + p.LastName; }) },
         new { Name = "Format", Action = new Action(delegate() { string x = string.Format("{0} {1}", p.FirstName, p.LastName); }) },
         new { Name = "StringBuilder", Action = new Action(delegate() {
            StringBuilder sb = new StringBuilder();
            sb.Append(p.FirstName);
            sb.Append(" ");
            sb.Append(p.LastName);
            string x = sb.ToString();
         }) }
      };

      var Watch = new Stopwatch();
      foreach (var t in tests) {
         for (int i = 0; i < 5; i++) {
            Watch.Reset();
            long Elapsed = ElapsedTicks(t.Action, Watch, 10000);
            Console.WriteLine(string.Format("{0}: {1} ticks", t.Name, Elapsed.ToString()));
         }
      }
   }

   public static long ElapsedTicks(Action ActionDelg, Stopwatch Watch, int Iterations) {
      Watch.Start();
      for (int i = 0; i < Iterations; i++) {
         ActionDelg();
      }
      Watch.Stop();
      return Watch.ElapsedTicks / Iterations;
   }
}

Console.WriteLine("User {0} accessed {1} on {2}.",
                   user.Name, fileName, timestamp);

Console.WriteLine("User {0} accessed {1} on {2}.",
                   user.Name, fileName, timestamp);

Console.WriteLine("User " + user.Name + " accessed " + fileName +
                  " on " + timestamp + ".");

Console.WriteLine("{0} {1}", p.FirstName, p.LastName);

Console.WriteLine(p.FirstName + " " + p.LastName);