When I last was asked to test the engine seemed fine...it is the artwork that needs attention.
The artwork could be "barrowed" from other games but that is not what the development team wanted.
The whole project was meant to be 100% TKC with nothing used from other games (engine/art).
Also the quoted fps are on machines and GPU's from 3 years ago.
With today's CPU/GPU the fps would be far higher still!