Faster way to repeat a string N times

Let’s say I’ve a string str = "squirrel" and I want to have a string str = "squirrelsquirrelsquirrel".
I wrote a function:

public static string RepeatString(string str, int n)
{
    string s = "";
    for (int i = 0; i < n; i++)
        s += str;
    return s;
}

But it seems to me that this code looks very unoptimized. Are there faster methods to achieve the desired result?

>Solution :

From the answer here:

In .NET 4 you can do this:
String.Concat(Enumerable.Repeat("Hello", 4))

In your case,

String.Concat(Enumerable.Repeat("squirrel", 3))