If you really want to run faster, you should try a new language. 30-40% for multiprocessing is nowhere near the benefit you'd get from a single threaded implementation in C, C++, Java, Rust, Ocaml, Go, or even JavaScript or LuaJIT. Those runs between 10 and 1000 times faster (1000% - 100000%) than Python.
> It's not that it helps in a particular way (though more on that below), it's just that starting with Python 2 now necessarily leads to rewrites later on. While you can see packages not supporting Python 3 (there are fewer and fewer of those), in the future you will see the opposite, some project already announcing end dates for their Py2 support (IPython to give an example).
So, there's no benefit to Python 3, but we should all migrate to it anyways? You think Python 2.7 will die, but trust me as soon as the PSF abandons it, someone will swoop in and become the new defacto supporter. For many of us, stability is a feature, and the fact that 2.7 won't change in gratuitous ways is super attractive.
> The clean break of 3 and the sanity it brings to the language is undeniable.
Well, I can't deny they broke it, but sanity is pretty deniable. Python has always been a dynamic language, and one of the core mantras was "there should be one obvious way to do it" (in contrast to Perl). All the new type annotation stuff and the multiple ways to handle string formatting are steps in very weird directions. Maybe they should make a Python version 4 to clean some of that mess up.