The author's surprise at the size of the ARC code seems to have led him astray from the actual bug in his code. The unoptimized version performs refcount manipu

The author's surprise at the size of the ARC code seems to have led him astray from the actual bug in his code. The unoptimized version performs refcount manipulation of 'id' and crashes. The optimized version avoids refcount mucking and does not crash. Seems to me this strongly implies that an invalid 'id' is being passed into the function!