Proposal for finalizer optimization.

[Ramón García]

I am thinking about optimizing the implementation of finalizing.

At present, finalizing imposes a high overhead to garbage collection.
If an object has a finalizer, it must be collected twice, in case the
finalizer creates a reference to the object somewhere. In the vast
majority of cases this does not happen. The optimization would detect
that the finalizer cannot create such references , and would mark the
finalizer to run exactly before the memory of the object is released.

What would be the best place to insert this optimization? Any other ideas?