Speed of String Concatenation

String Concat.cs

var s1 = string.Empty;
var s2 = new List<string>();
var s3 = new System.Text.StringBuilder();

var sw = new Stopwatch();
const string Message = "Hello I am string number {0}";

sw.Restart();
for (int i = 0; i < 30; i++) {
	s1 += string.Format(Message, i) + "\n";
}
sw.Stop();
s1.Dump($"String concat in: {sw.ElapsedTicks}ms");

sw.Restart();
for (int i = 0; i < 30; i++) {
	s2.Add(string.Format(Message, i));
}
s1 = string.Join("\n", s2);
sw.Stop();
s1.Dump($"List in: {sw.ElapsedTicks}ms");

sw.Restart();
for (int i = 0; i < 30; i++) {
	s3.AppendLine(string.Format(Message, i));
}
s1 = s3.ToString();
sw.Stop();
s1.Dump($"StringBuilder in: {sw.ElapsedTicks}ms");

Results:

• String concat in: 152ms
• List in: 95ms
• StringBuilder in: 44ms