Probably worth noting that the presentation that the author is discussing is less about 'which language is faster' and more about what sort of abstractions different types of languages encourage.

The presenter explicitly takes the position that Go and Python (actually PyPy) should be equally fast given the same sort of operations. Just that Python's idioms tend to be less efficient. He's a PyPy developer too, so I would think he would know something about what's going on under the hood. (He also talks a bit about why the VM doesn't/shouldn't try to optimize these cases automatically. Worth a look, it isn't long.)