In delphi sydney, does setting [weak] in front of an object (not an interface) make a penalty ?
Exemple :

  TMyObject = class(Tobject)
  Private
    [weak] FOwner: TMyObject;
    ....
  end;

I ask because I know that internally [weak] references are stored in a list and thus it's have some drawbacks (regarding speed). As now with Sydney ARC is gone there is no need anymore to put [weak] in front of an object (as far as I know), but as I want to keep my code compatible with Rio and less I ask if I can safely leave the [weak] reference without suffering of useless performance lost (in sydney)

there is a teeny-weeny problem with the [weak] attribute. It denotes a
zeroing weak reference that will be zeroed (niled) when the object it
points to is no longer valid. In order to do that, the compiler has to
track such objects at runtime and that introduces some overhead. If
you are tracking many such references, that can introduce a
significant performance loss.

回答

var
  Obj: TObject;
  [weak] WObj: TObject;
begin
  Obj := TObject.Create;
  WObj := Obj;

  Obj.Free;
end;