Python 2.7 has terrible thrashing in the way the GIL is acquired that is exacerbated as more threads are used. Dave Beazley has given great talks with the tech

Python 2.7 has terrible thrashing in the way the GIL is acquired that is exacerbated as more threads are used. Dave Beazley has given great talks with the technical details: http://www.dabeaz.com/GIL/ http://www.dabeaz.com/GIL/