Hi @pyr,
In Python, there is a GIL which do not allow Python by design to execute something in parallel.
In Cinema 4D all our functions (so everything which is in the c4d python module) is "GIL safe" in order to avoid any issue with Python memory.
So in Cinema 4D thread are designed for doing GUI, or background stuff.
Moreover, keep in mind creating a Thread have a cost in term of time (to create, execute, delete them).
Finally, I would like to point you to multiprocessing vs multi-threading.
Note that since it's more an algorithm problem than an issue related to our API, we can only provide you hints.
btw, I also turned your topic as a question. See Q&A New Functionality.
Cheers,
Maxime.