The people who did the work on finding and implementing this speedup talk about it here. https://fedoraproject.org/wiki/Changes/PythonNoSemanticInterpositionSp

The people who did the work on finding and implementing this speedup talk about it here. https://fedoraproject.org/wiki/Changes/PythonNoSemanticInterpositionSpeedup https://fedoraproject.org/wiki/Changes/PythonNoSemanticInter... They then proposed it for upstreaming here: https://bugs.python.org/issue38980 https://bugs.python.org/issue38980 And that's the new default. The link is to a facebook post by someone who neither discovered nor implemented this change.