OK, let's get things more straight: * Threads are useful not just for speeding up, but also for parallel execution (storege/network io, graphics, ...) * If yo

OK, let's get things more straight: * Threads are useful not just for speeding up, but also for parallel execution (storege/network io, graphics, ...) * If you really care about speed and would like to parallelize CPU-bound code, you'll probably do better using another language like C/C++ (or Java, Go, D etc.) for this particular task * In general, threads are used instead of processes because of the overhead involved in creating the latter * Python multiprocessing module isn't the most efficient anyway, for example when passing large objects between processes because of the way they're serialized * It also has some other quirks so I would definitely not advise to use it for "everything".