I have kept backup files,usually after editing the game crashed or would look silly (missing textures,blinking grafix,slooooooow,lock up)and processor rate would go up to 180% if it worked,this game was not design for mods thats for sure..
When using my backup files,gp4 wouldn't start for some reason usually just a black screen(with locking pc),as a result.
The only way was to copy the hole Gp4(backup) on different harddrive or installing again.
Use high resolution on Gp3,for me it looks great and runs smoothly.
Gp1 & Gp2 where excelent games!
Gp4 if it worked would play at around 14-17 fps and would slow to nothing when it started to rain.Looked more like a frame show 4-8fps.....
Patching game wouldn't help on my problems either.
With my pc specs i would think it would play faster.....
These are just my opinions
and to those that Gp4 works and runs fast,keep on racing and editing.