The FSX Autogen tweak

Sorry to be so naive, but what IS the "autogen tweak" which presumably increases FSX performance? Please be specific.I bought FSX yesterday and ran it. Mildly satisfied, missions are OK, but cities are very poorly represented, mostly by flat gray square blurs. Denver, for example, is represented by the football stadium, a few generic tall buildings, and the rest of the city is essentially flat. The freeways are awful. Just blurry lines, no definition. So much for the claim that one can see traffic moving, on roads.Bob