Performance regression with libstdc++-v3

[Benjamin Kosnik]

> > Benjamin/Phil, do you remember off-hand why the __USE_MALLOC
> > configuration of the allocator was selected? 

There were a lot of MT issues with __USE_MALLOC and libstdc++-v2. Turning 
it on became a quick way of fixing these issues without re-writing the 
allocator class. 

> > If not, we might want to
> > seriously reconsider the selection before the 3.0 release (I know it
> > is *very* late to be suggesting this change, but STL code running
> > about three times slower than it could will be an important turnoff to
> > people we are trying to convince that g++ 3.0 and libstdc++-v3 is
> > ready for prime-time).

Right.

Thanks for the good analysis on this one Loren. I'm up for this change, 
and would approve it for both branch and mainline if you were to make a 
patch.

best,
benjamin