Web Forms :: String And StringBuilder - Any Change Updates Memory Location Rather Creating New

String is immutable and StringBuilder is mutable. So if I change the value of a string a new memory created with the new value, whereas in StringBuilder it updates its memory location rather than creating a new memory location. So for large concatenation stringBuilders are preffered. But when I create a new String object, a fixed memory is created. And any changes will update its memory location, rather than creating a new memory location.

For e.g.
String s = new String();
s = String.Empty;
for ( int i=0;i<100; i++)
{
//s = s + "test" + i.ToString();
s =string.Concat(s, "test" + i.ToString()); ///This is effecient compared to previous step
}

Now instead of String class I will use a StringBuilder class.

StringBuilder s = new StringBuilder(String.Empty);

for ( int i=0;i<100; i++)
{
//s = s + "test" + i.ToString();
s.append( "test" + i.ToString());
}