I think a choice of distance rendering a la "Oblivion", could be implemented ( if engine permits it ) in the game, and ppl with mid/low range system could just choose the distance themselves without a perfomance hit choking the PC
Very rarely the game themselves messes up the PC. It is mostly the "enviroment" the game has to run in that causes most of the problem.
The daily dose is: Registry Cleaner, clean junk files (temp and so on). Did you know that left-over typed URL's can mess up so an application ( read: game ) won't run properly. Missing / broken links for example, can make so an application won't run, also, check the save files logs,,there are perfomance "eaters" in there, the save folders GROW fast.
There are 100:ed of things that doesn't have anything to do with the game software really, that can make a game not run properly.