I was actually just working on this now. It not only helps improve performance but gives it a nice creepy effect with the shading around the players field of view.
Regarding the slow-down when approaching corners due to the multiple rays hitting: I have been working to make npcs appear, and have figured out a way. I put the npc images as animations of the walls, then set an instance variable for the ray obstacle for the npc, which passes from the obstacle to the sensor to the wall with an extra condition during wall creation. I put an npc in a corner, and it helps the lag a little by deflecting some of those rays from hitting the same spots.
However, it creates a minor display bug in the wall behind the npc, since the rays don't pass through it.
