Autogen tweak

I've just read in one post that the autogen can be tweaked so that a relealistic and framerate freindly autogen can be achieved.
I've read through the FAQ section and I'm having difficulty locating the fsx.cfg file.
I've ticked 'show all hidden folders' and I've searched on XP search icon using the exact file name mentioned above.
I'm not getting anything, exept a readme file on an introduction to FSX.
Autogen does effect my framerate especially in the most critical stages of flight, 'landings'. So it is imperative that I get this sorted.
Are there any exact strings to follow, er, ie folders that you could follow me through into?
I've read through the FAQ section and I'm having difficulty locating the fsx.cfg file.
I've ticked 'show all hidden folders' and I've searched on XP search icon using the exact file name mentioned above.
I'm not getting anything, exept a readme file on an introduction to FSX.
Autogen does effect my framerate especially in the most critical stages of flight, 'landings'. So it is imperative that I get this sorted.
Are there any exact strings to follow, er, ie folders that you could follow me through into?