IronPython vs CPython: faster in 1.6 times?

[dmitrey]

Hi all,
the url http://torquedev.blogspot.com/2008/02/changes-in-air.html
(blog of a game developers)
says IronPython is faster than CPython in 1.6 times.
Is it really true?
If yes, what are IronPython drawbacks vs CPython?
And is it possible to use IronPython in Linux?

D.