You forgot dynamic property creation/lookup instead of using a constant "shape" that JS engines can actually JIT optimize away.

And then there's the more detailed version of that where people write {x: 0, y: 1} in one spot and {y: 1, x: 0} in another and do not seem to realize that this under the hood they just sabotaged the ability of every JS engine out there to fully optimize any code related to it. Which also extends to situations where functions take objects that happen to share some properties as parameters: if you can put the shared properties first and in the same order in the object creation, it will result in better optimized functions.

(but tbh I think that as long as we don't fix the bloat that is tracking libraries first, all of this is optimizing the wrong thing)