alt Hacker Newskeep in mind that, apart from the money throw at js runtime interpreters by google and others, there is also the fact that python - as a language - is way more "dynamic" than javascript.
Even "simple" stuff like field access in python may refer to multiple dynamically-mapped method resolution.
Also, the ffi-bindings of python, while offering a way to extend it with libraries written in c/c++/fortran/... , limit how freely the internals can be changed (see the bug-by-bug compatibility work done for example by pypy, just to name an example, with some constraint that limit some optimizations)
> python - as a language - is way more "dynamic" than javascript
Very true, but IMO the existence of PyPy proves that this doesn't necessarily prevent a fast implementation. I think the reason for CPython's poor performance must be your other point:
> the ffi-bindings of python [...] limit how freely the internals can be changed