How Expensive is String Concatenation?

[weicool]

I read in the FAQ thread that string concatenation in PHP (the dot . ) is expensive. I was just wondering HOW expensive it is. I know that in Java, the String object is immutable, so concatenating Strings using the + operator will cause Strings to be first copied and then glued together. Is that the way PHP works?

[Dan Grossman]

10,000 string concatenations averages two thousandths of a second on my server. It's a non-issue, isn't it?

[logic_earth]

There are far more expensive things then concatenation. Please focus on those not these already beyond optimizing ideas. There is no way to make:

$s = 'data';
$s = $s . ' more data'; 

go any faster so stop trying. It is as fast as its going to get. (abit simplistic example)