StringBuilder vs. String / Fast String Operations with .NET 2.0

对字符操作 比较 介绍比较详细的文章。
http://www.codeproject.com/KB/cs/StringBuilder_vs_String.aspx

String Operation	Most Efficient
Insert	StringBuilder.Insert > 2 Insertion Strings String.Insert otherwise
Remove	StringBuilder is faster > 2 characters to remove
Replace	String.Replace always
Format	String.Format < 5 Append + Format operations StringBuilder.AppendFormat > 5 calls
Concatenation	+ for 2 strings String.Join > 2 strings to concatenate