Is there a performance difference between a for loop and a for-each loop?

Question

What, if any, is the performance difference between the following two loops?

for (Object o: objectArrayList) {
    o.DoSomething();
}

and <

Answer 1

It's always better to use the iterator instead of indexing. This is because iterator is most likely optimzied for the List implementation while indexed (calling get) might not be. For example LinkedList is a List but indexing through its elements will be slower than iterating using the iterator.