
You appear to be on a Dec ALPHA with only gcc newer than 2.8 installed.
Gcc does a better job optimizing generated code than DEC's cc.  It appears
that DEC's cc reserves several registers (probably for use in software
pipelining), and that prevents ATLAS from achieving maximal performance.  

The second rather surprising result on ALPHAs is that EGCS and new versions
of gcc produces much less optimal code than gcc 2.8 or earlier.  You will
lose roughly 10% of performance by using newer gcc.  The errata file
   www.cs.utk.edu/~rwhaley/ATLAS/errata.html
contains pointers to instructions on downloading and compiling an old version
of gcc.

If you continue the ATLAS install without first installing gcc 2.8 or earlier,
your performance will be about 10% below what you could achieve.

