Fastest way to convert a list of strings into a single concatenated string?

Question

I have some LINQ code that generates a list of strings, like this:

var data = from a in someOtherList
           orderby a
           select FunctionThatReturnsS         


        

Answer 1

How about:

public static string Concat(this IEnumerable source) {
    StringBuilder sb = new StringBuilder();
    foreach(string s in source) {
        sb.Append(s);
    }
    return sb.ToString();
}

and:

string s = data.Concat();

This then has no need for the extra ToList() / ToArray() step.