StringBuilder only gives you gains if you are concatenating the same string over multiple lines of code. If you care creating the string in a single line, StringBuilder just gets in the way.


>Do you mean instead of StringBuilder?
>
>I figured out the missing piece (I just needed to specify the number after the parameter, e.g. {1,11:N0}) but somehow my unit test was still failing although visually to me the output looked exactly the same.
>
>I decided to trust the visual output and switched to a different method now.