Use Scissors instead of Stencils for performance

Specifically I'm interested in @edisonout trying this out to see if it improves the performance problems in the hallway as the splatters are added to the level. I know for me that every hippy I kill in the hallway slowly drops the framerate because of all the stencil drawing.

Also, I'm not sure why the height calculations are off and need to be multiplied by a factor of 2 in order to work. Anyone have any ideas?