Question

Is this:

foreach(Type item in myCollection)
{
   StringBuilder sb = new StringBuilder();
}

much slower than:

StringBuilder sb = new StringBuilder();

foreach(Type item in myCollection)
{
   sb = new StringBuilder();
}

In other words, will it really matter where I declare my StringBuilder?

Answer 1

You could maybe gain some performance, if you write this:

StringBuilder sb = new StringBuilder();
foreach(Type item in myCollection)
{
   sb.Length = 0;
}

So you have to instantiate the StringBuilder just once and reset the size in the loop, which should be slightly faster than instantiating a new object.