Faster compilation speed

[Aldy Hernandez]

> I don't think Mike mentioned it, but speeding up the compiler has
> become our group's top priority, and every idea is on the table
> right now.  The 6x goal sounds extreme, but it helps keep in mind
> that one or two or even a dozen 5% improvements will not be
> sufficient to attain parity with the competition.

Fair enough.  Game on, and good luck.

And please don't keep your changes in your tree, and then have them
become obsolete in 4 months when you try to merge :)

Aldy