I've implemented a custom Python Node for Houdini's SOP-Context.
Under certain conditions (e.g. Deformer, attribute creation & modification), it can speed up execution of a Python node in the SOP-Context up to 2 times.
Here's a video about it at Vimeo: Fast Python node [vimeo.com]

If you are interested in trying it out & giving feedback, I can make the plugin available for download (Linux & Windows).

As a clarification: The custom FastPython node does not speed up the execution of Python as such in Houdini.
But it allows to tell the Houdini SOP cooking engine which parts of the geometry & attributes it can reuse / cache.
This speeds up the execution of the FastPython node compared with the standard Python node in the mentioned conditions.

I will also upload a video soon about using Numba [numba.pydata.org] to speed up Python in Houdini on Linux & Windows (it's a bit more complicated on Windows… )
Edit: Done, see this thread: How to use Numba with Houdini [www.sidefx.com]

Thanks for any feedback & potential questions

I have attached the Linux and Windows versions of the FastPython node plugin and 1 example file to this post.
Installation instructions are included.

Have fun & thanks for feedback and/or comments

Thank you svenkr for you hard work much appreciated.