OSMBright incredibly slow for osm2pgsql output

I used osm2pgsql to load the OpenStreetMap planet.osm.pbf file into Postgres (27 GB in .osm.pbf format, ~350GB in the database). Now when I open the OSMBright project in Tilemill, all of machine's cores light up but no tiles show up. After waiting 5+ minutes layer 0 tiles show up and then a smattering of layer 1 and 2 tiles, but then it seems to stall out. Any ideas on what the bottleneck would be?

Is it possible that some index didn't get built in the database so it's doing some kind of much slower search? Or maybe I need to allocate more memory to Tilemill or Postgres?

I followed the instructions here
https://www.mapbox.com/tilemill/docs/guides/osm-bright-mac-quickstart/
for setup.

Thanks!
Ben

Some specs:
MacBook Pro, OS X 10.9.5, 16GB RAM, 8 CPUs, 100+ GB free disk space

Start with the OSMBright project, the osm2pgsql/Postgres loading setup, and the OSM Bright Mac quickstart linked in the issue. Reproduce tile generation in Tilemill and investigate whether database indexes, memory, or another bottleneck explains the delay; done means identifying and documenting a concrete cause or configuration fix.