Only if you label basically everything as &quot;legacy&quot;, which is really stretching the definition. Just because someone invented a New Thing, doesn&#x27;t mean all the Other Things are suddenly &quot;legacy&quot; overnight.<p>Fact is, PyPy may be &quot;fast&quot;, but in science CPython is in effect much faster because you can use the massive and optimised scientific stack including python, pandas, hdf5, etc etc