...will there be any performance gain regarding advancements in programming,..seeing the years are ticking by

They do seem to be getting more efficient... the amount of detail in the J41 versus the MD-11 is huge for about the same performance (at least on my machine). And the 737NGX will probably be even better.

Probably. Apparently the new -8i has better FPS than the original -400X, just due to improved modeling of the exterior. I would guess that the NGX will have similar performance to the JS41, as it will probably be more efficient, but will include more systems.