vvis determines what faces are visible to the player, it has nothing to do with lighting. There can be faces that are pitch black but vvis will still consider it visible.

The way to cut down on visible faces is to use the lovely nodraw. You can further optimise by using hints which will only draw players and props in certain places, or occluder which won't draw any model at all on the other side of it (place these insides walls and such). func_detail is also your best friend.

Learn how to handle areaportals because using them correctly can increase the fps tenfold.

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