Brad Abrams, .NET Framework PM, posted this interesting tidbit about using the Length property of an array directly in a loop as supposed to assigning it to a local variable. For example:
int length = myArray.Length;
for (int i=0; i<length; i++)
for(int i=0; i<myArray.Length; i++)
If you have time, I suggest you read it. You'll be surprised on how the framework handles this issue.