Originally most of the new Autogen textures are in 512X512 format, while night Autogen textures are in 256X256 format.
Tree Texture are in 1024X1024 format, enormous and really unnecessary.
I decided to cut the size by 50% reducing the filesizes thus improving the overall framerate (FPS).
I noticed that flying over a very large city (like Los Angeles) is much smoother, even with the "Autogen" slider set to maximum.
The difference of detail in my opinion is minimal.
NEW AUTOGEN TEXTURES--FS2004 VERSION:
Day Autogen textures are cut in half, from 512X512 to 256X256.
Night textures are cut in half, from 256X256 to 128X128.
Tree textures are reduced by 75%, from 1024X1024 to 256X256.
OLDER AUTOGEN TEXTURES--FS2002 VERSION
All of the older Autogen textures are cut in half.
If you decide to resize some more textures in FS...
here is the list of the formats you should maintain.