Optimizing structures on a box map

I'm wondering how to best optimize my first map which is effectively an outdoors open box with scattered houses in terms of geometry. Specifically the houses which are pretty prop dense.

I've watched guides on hints/areaportals, and I'm not sure how well hints work with sealing up something like a house with multiple windows. I've tried using areaportals on one of my houses and it works fine, but I've been told they can be costly for people's cpus, I don't really know where to draw the line on when it's worth it to have area portals calculating a room or just have the props inside rendered.

Since I've stuck myself with this box shape I understand there can't be as much done to optimize it compared to a map designed with visibility in mind. I've been going through optimization checklists and getting nodraw on unseen faces, trying to line up brushes correctly, and get proper fade distance onto my many props but want to know if there's anything I might be not be aware of with optimizing this box of mine.
Thanks for any suggestions!

Xbmann said:

You should look into func_areaportalwindow as well as prop fade distance for specifically expensive props. Also are you sure you couldn't make the terrain uneven and able to block off different parts of the open box similar to blacksite on cs:go?

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I'll be sure to use areaportal windows, I can see why they might be better at plugging up buildings with lots of view holes.

In place of terrain I have a train splitting down the middle with buildings and rocks cutting annoying sniper sightlines, but being a redesign of a very flat old timey western map I'm having a hard time thinking of how I could implement the terrain type of the map you suggested, as well as balancing them around tf2 dm with a high skybox. Thank you for the suggestion on that though, only playing tf2 I haven't seen any good examples of really open maps through my playing and I'll be sure to keep it in mind if I make another open map.

Prop fade distance I've already implemented, but without terrain like blacksite my outdoor props are generally forced to have very long fade start distances.
Fortunately it's a moderately small map so if using func_areaportal(window)s won't be too expensive to seal up my 6 buildings (averaging 4 total doors/windows each) I feel like I can get it to a good spot.

nesman said:

take a look at this guide https://www.mapcore.org/articles/development/optimizing-an-open-map-in-source-engine-r88/

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Thanks for the guide! This was just what I needed and am setting up a basic hint system now.

I'm wondering about the relationship between these hints and func_visclusters. Visclusters have been saving my butt with compile times but I'm not completely sure on how they work besides reducing visleaves that see eachother in the area. Will my visclusters that overlap with my hinted visleaf compartments basically delete them?