More than 11 years after the release of CRUX 0.5 for i686, CRUX 3.0 is the first release for the x86-64 architecture.
At the time Per Liden had created CRUX, the i686 processor on base of the 32-bit Intel IA-32 architecture was state
of the art and therefore chosen by him as the default optimization for CRUX. But nowadays the IA-32 arch is more
or less obsolete, at least for desktop machines, and superseded by the x86-64 architecture.