> Do we even use PGO to the fullest extent?  Does someone actually build an
> instrumented Python, run training inputs on it, and then rebuild with the
> training data to take advantage of the profile-guided optimizations?

Yes, I do, on every release of Python. The test set includes at the minimum
"Tools\pybench\pybench.py -n1 -C1 --with-gc". I used to also include
"Lib\test\regrtest.py". Now, some recently added tests have slowed this down
so much that this is not feasible anymore in PGI mode.

This issue wouldn't have been reported in the first place if this  
feature wasn't
used; see also msg107124.

I don't mind just not doing it anymore; it speeds up the release process.

> If not, then I doubt PGO is buying us anything anyway.

It was originally added because people reported measurable speedups when
profile-guided optimization is used, for VS 2008.

> I noticed when building with VC++ 2010 Express on the PGI/PGO builds that it
> warns about PGO not being available.  I don't know what version we build our
> Python release bits with.

I do, of course, have at least a professional edition of Visual Studio to make
the Python releases available from www.python.org. More specifically,  
my VS 2008
installation is "Professional"; my VS 2010 installation is "Ultimate".