使用+'s分配单个字符串值的性能成本是多少

I have often wondered this, is there a performance cost of splitting a string over multiple lines to increase readability when initially assigning a value to a string. I know that strings are immutable and therefore a new string needs to be created every time. Also, the performance cost is actually irrelevant thanks to today's really fast hardware (unless you are in some diabolical loop). So for example:I have often wondered this, is there a performa