1. Armin Rigo
  2. psyco


Psyco, the Python Specializing Compiler

Psyco is a Python extension module which can massively speed up the execution of any Python code.


Psyco works on almost any version of Python (currently 2.2.2 to 2.5). At present it requires a 32-bit architecture, but it is OS-independant. It can only generate machine code for 386-compatible processors, although it includes a slower emulation mode for other (32-bit!) processors.

This program is still and will always be incomplete, but it has been stable for a long time and can give good results.

There are no plans to port Psyco to 64-bit architectures. This would be rather involved. Psyco is only being maintained, not further developed. The development efforts of the author are now focused on PyPy, which includes Psyco-like techniques. (http://codespeak.net/pypy)

Psyco requires Python >= 2.2.2. Support for older versions has been dropped after Psyco 1.5.2.


To install Psyco, do the usual

python setup.py install

Manually, you can also put the 'psyco' package in your Python search path, e.g. by copying the subdirectory 'psyco' into the directory '/usr/lib/python2.x/site-packages' (default path on Linux).

Basic usage is very simple: add

import psyco psyco.full()

to the beginning of your main script. For basic introduction see:

import psyco help(psyco)


Home page:

The current up-to-date documentation is the Ultimate Psyco Guide. If it was not included in this distribution ("psycoguide.ps" or "psycoguide/index.html"), see the doc page:


To build a version of Psyco that includes debugging checks and/or debugging output, see comments in setup.py.