Well, it is not exactly killing performance, but values()[num] should do
the trick.

again, iterate over values(). This is an array, and therefore iterable.

There is a static method values() on enum types that returns an array of the
enum's values in declared order.
You can iterate over an array using the enhanced for loop, but it's not an
actual Iterator instance.

As for question 1:
You could also create a method of your enumerated type to return the
instance of the int you want. If you use a constructor then you will ruin
the singleton pattern generated by the enum type declaration.

public enum OneOfThree
{
 ONE, TWO, THREE;

 public OneOfThree get(int i) throws Exception
 {
   switch (i)
   {
     case ONE.ordinal(): return ONE;
     case TWO.ordinal(): return TWO;
     case THREE.ordinal(): return THREE;
     default: throw new Exception("Invalid argument");
   }
 }
}

I'm sure others have different ways to do this, too.
You could also return the instance from the values() array at the ordinal
index passed,
 return values()[i]; // if 'i' is in range

Also see:
http://java.sun.com/j2se/1.5.0/docs/guide/language/enums.html

--Paul