I see Javascript 6 will add traditional class based inheritance, and one argument I hear is that classes are inherently much faster than prototypes because they can be optimized away by the compiler when doing (JIT) compilation to native code or to bytecode. That sort of makes sense to my mind, but I'm not nearly an advanced enough programmer to really understand this stuff.

The argument I always saw for prototypal inheritance (PI) was that it conserves memory, which is mostly a completely moot point these days. Personally, I like PI and always felt it "makes sense" in a dynamic language; like it is a luxury you can just as well afford if you already settled for the performance limitations of an interpreted dynamic language.

In C++, classes makes sense because of the limitations that comes with the C++ philosophy that everything takes a back seat to maximum possibility for performance.

Of course you can have PI in C++ and there is a well known design pattern for that, but I'm talking about built-in inheritance in a dynamic language.

**If one was looking at the fastest possible implementation of prototypal inheritance in a fictional dynamic language, what would necessarily be the drawbacks with regards to performance vis-à-vis traditional classes?**

**What if you add the feature to the fictional language that you can specify that some objects are "final" and their prototype chain cannot be changed at runtime? (Coexisting with traditional PI) Also add optional static typing or type hinting if that helps the prototypal language.**

Since this might be considered a bit of a vague question, I'm adding:

I guess I'm looking for the thoughts on the subject from people who are more clever and more interested in language theory and/or compiler/interpreter writing than me. Hope that is still an ok question.

This is not about Javascript 6 at all, I just brought it up because Javascript is the most successful prototypal language and it is interesting that they are adding native classes even though Javascript seemed to be doing fine without them (both popularity wise and having some jaw-dropping benchmark improvements in the last few years). I'm also not saying that I believe or think that Javascript is slow.

Really, I'm more interested in learning more about programming languages, possibly with the goal of some day constructing my own dynamic language.