-This is a map view shown from the top down. As you can see, there are three sections to this map: the left room, the right room, and the top hallway. Now, let's say the player is in the left room. The player can't see into the right room, but can partially see into the hallway. However, since there are no hint brushes and the rooms are not completely separated by structure brushes, the whole area is rendered for the player because the hall and right room are in the same "leaf." This means an FPS drop due to the unneeded drawing.
+This is a map view shown from the top down. As you can see, there are three sections to this map: the left room, the right room, and the top hallway. Now, let’s say the player is in the left room. The player can’t see into the right room, but can partially see into the hallway. However, since there are no hint brushes and the rooms are not completely separated by structure brushes, the whole area is rendered for the player because the hall and right room are in the same “leaf.” This means an FPS drop due to the unneeded drawing.