Goldrush: All those brushes -> Info wanted

[BroQ]

When I look into th goldrush map in my gtk-radiant, I always see that almost every square brush is divided in 2-3 different brushes. why do you do somthing like that while you just can easely make the square brush?

Info wanted

[Blackadder_NZ]

Its so less triangles are drawn which in turn means a lower r_speeds which means in the end better FPS for players.