If you dig into JS engine implementations they deal with a lot of the same sorts of things. Simple objects with straightforward properties are tagged such that they skip the dynamic machinery with fallback paths to deal with dynamism when it is necessary.

A common approach is hidden classes that work much like classes in other languages. Reading a simple int property just reads bytes at an offset from the object pointer directly. Upon entry to the method bits of the object are tested and if the object is not known to be simple it escapes into the full dynamic machinery.

I don't know if those exact techniques would work for Python but this is not an either-or situation.

See also: modern Objective-C msg_Send which is so fast on modern hardware for the fast-path it is rarely a performance bottleneck. Despite being able to add dynamic subclasses or message forward at runtime.