Imo having improved performance on the new engine is even more important than visual improvements to textures/lighting etc.
Areas like newb isl (alien area) and the APF base have horrible FPS on my new laptop that is capable of playing new games (e.g. bf3) which have awesome graphics and playable framerates.
The engine needs to be made more efficient for modern PCs with multicore cpus and dedicated gpus. And I hope this will be the case.