Perhaps they were not comparing the performance, but just trying to explain their product? However, it also says in the paper:

"Originally we created a technology demo using the Quake 4 assets. The demo created an FPS on top of the standard Turbulenz Engine but implemented a modern deferred renderer in place of Quakeʼs original forward renderer. Once we had this multiplayer demo running at over 60 fps with particle effects, full screen effects, character animations, a full physical environment, 3D audio, networking and the deferred lighting solutions, we decided that JavaScript was absolutely capable and suitable for creating modern games."