Yes, that's correct, but if you are using semi-complex objects, then you have to invoke the python interpreter and lose most of the advantage of going to Cython

Yes, that's correct, but if you are using semi-complex objects, then you have to invoke the python interpreter and lose most of the advantage of going to Cython in the first place. Even for things like ints, floats, etc - if you want to see a significant speed up, you have to convert them into c ints and floats.