After reading this thread yesterday I pulled the contents of the pk3, decompiled the bsp, and started tinkering. Not surprised that removing the particle systems didn't do much (though I would remove them anyway, just kinda gimicky). After getting dizzy looking at all the hint brushes, I deleted them all.
***Then I realize, absolutely no detail brushes! (Might be wrong, see note below :oops:)*** I didn't even bother loading up the portal file to see where all the vis planes were going. Found overlapping brushes, overlapping faces, brushes and faces that should be caulked, and brushes that could probably be merged (may need some texture tweaks though). Also, there are several spots where patch meshes were used, but instead of just caulking behind them, pretty much the whole map is coverd in a caulk hull (and not well placed in some areas). While the map is a peice of art, the engineering underneath is a nightmare.
Well, since everyone needs a hobby, I'm going to be messing with this in my spare time. I intend to try not to touch anything relating to its "art", just optimize the map. No guarantee I will ever finish. If anyone wants to help I might look into setting up a Subversion repository (anyone know how well a map will work in SVN?). If anyone comes up with the original map file within the next week or two, could you please send it to me. And if anyone hears that the original mapper is going to work on it, then I'll stop

.
MAJOR EDIT: Wait, detail brushes don't come in a decompile, do they? Thought I decompiled Metro, but just rememberd the map file was included, so that threw me off. :oops: