[postal2mac] First impressions

[Ryan C. Gordon]

> There are also some differences between how the PC and the Mac handle 
> AGP memory, so you cannot directly compare the two.

Most specifically, there's no AGP aperture on the Mac. You can assign
almost all your system RAM (it's not VRAM, the VRAM is something else
entirely) to AGP. MacOSX caps it at 25% of your system RAM, and you
can't allocate a vertex_array_range block that is more than 75% of this
space.

So if you set VARsize to something bigger than around:

  (0.75 * 0.25 * total_memory)

Then it'll probably fail. If you ask for too much VAR, you get none, and
everything is REALLY slow. If you ask for too little, you fall off the
fast path, and everything is REALLY slow.

Naturally, the larger you set this, the more memory you're consuming.
Feel free to experiment, but while bumping it up a little might help,
it's a black or white thing: you either have enough VAR for the
rendering, or you don't. Once you have enough allocated, adding more
doesn't improve performance, but it does take away from available RAM.

It's a zen art, basically. Or, leave it at 32.  :)

--ryan.