This should eliminate the missing road and city texture loading problem for laptops/desktops with low vram I set the bytes to 536870912
which equals 512mb exactly others are reduced values to maximize performance this totally eliminated the missing texture problems for me.

Place this in the main GTA 5 directory.

Also I suggest using low spec trees and grass which can also be found here on this site: :-)

https://www.gta5-hub.com/misc/lower-resolution-grass-for-improved-performance