Replace your gta_sa.exe with this gta_sa.exe (in the folder ''Stream Memory fix'' in this rar)
Then put stream.ini and StreamMemFix.asi in your
GTA Sa Directory/Folder (where gta sa is installed).
This will fix all the bugs you get from detailed/highquality mods, it will clean all the problems with map dissapearing, slow map loading and lag you get from a car mod.