Lee Killough is a well-known programmer who has contributed to the development of Doom source ports. He was part of the Boom team, and is the author of Marine's Best Friend. Killough notably added many performance optimizations to the Doom engine. The single most important efficiency improvement was replacing the linear search used for looking up game data resources with a hash table algorithm. This improvement sped up the engine over 300%.1 In addition to working on source ports, Killough developed BSP after Colin Reed.