PyPy is a reimplementation of Python in Python, using advanced techniques to try to attain better performance than CPython. “Many years of hard work have finally paid off. Our speed results often beat CPython, ranging from being slightly slower, to speedups of up to 2x on real application code, to speedups of up to 10x on small benchmarks. In the spring of 2009 we completed an update of PyPy to support Python version 2.5 with much appreciated financial support from Google. Most of the work on the update was done by Maciej Fijalkowski and Samuele Pedroni. While this work was in progress, Armin Rigo and Carl Friedrich Bolz were hard at work rebuilding the framework of the Just In Time compiler (JIT). The old framework, using techniques based on Partial Evaluation, only gave good results in constrained cases, but it would usually generate far too much code for Python,” states Google.
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