Feedback UI in its own/separate scene or everything in same scene?

Hi guys.
This is more of a general question but based on your experience, it would help me a lot before I break things.

Is it better performance-wise to have the UI in its own scene and load other scenes for the rest of the game? or is it better to have the same UI in all my scenes altogether?

Initially, for "maintenance" and reusability, having the UI in its own scene sounds better, but not sure if having two scenes running/loaded simultaneously (the scene for the UI and the current scene for the actual game), would be more costly than having everything in just one scene (even if that implies to duplicate the UI in every scene)

Thanks.