Hi,

At Wed, 1 Mar 2006 19:39:15 +0900,
Tanaka Akira wrote in [ruby-core:07468]:
> The performance issue exists.  However I'm not sure that it
> is significant because Kernel#object_id is used not so
> common.  ObjectSpace._id2ref is used rarely and it should
> be.

rb_obj_id() is used as Kernel#hash also.

-- 
Nobu Nakada