Most efficient way to concatenate strings?

Question

What\'s the most efficient way to concatenate strings?

Answer 1

From this MSDN article:

There is some overhead associated with creating a StringBuilder object, both in time and memory. On a machine with fast memory, a StringBuilder becomes worthwhile if you're doing about five operations. As a rule of thumb, I would say 10 or more string operations is a justification for the overhead on any machine, even a slower one.

So if you trust MSDN go with StringBuilder if you have to do more than 10 strings operations/concatenations - otherwise simple string concat with '+' is fine.