Thank you, I think I just needed to read more carefully. Compared to the spread operation ("naive handcrafted reducer"): > [Mutative] focuses on shallow copy

Thank you, I think I just needed to read more carefully. Compared to the spread operation ("naive handcrafted reducer"): > [Mutative] focuses on shallow copy optimization, more complete lazy drafts, finalization process optimization, and more. Compared to Immer: > Immer relies on auto-freeze to be enabled, if auto-freeze is disabled, Immer will have a huge performance drop and Mutative will have a huge performance lead, especially with large data structures. Oh, I didn't notice this: Full compliance with JSON Patch specification. Interesting!