| Splitting plane choice probably varies between the various engines. For my bsp builder, I actually try every single plane until I get the most balanced results. This is tremendously slow, but I plan on having small levels in my game. I only use the bsp for collision and ray casts and such, so I want them to cost the same in all areas of the map.
In the old days the visible surface area was always a big hit on performance, but not sure it matters anymore. Not even really sure if modern engines use static lighting like lightmaps. Mine does.
In my compile tools also, things can go haywire if a surface is large enough that the resulting lightmap goes over 4k. Not really sure what happens as I haven't hit that yet. | 