Maybe try modded game folders that are created to increase fps for low spec pcs , maybe ram doesnt make a difference for samp ???
http://www.mediafire.com/file/wwbbyjvo1beqh59/gta+for+waka+encore.7z/file
http://www.mediafire.com/file/ux5c1wr3pma43gl/Lewis+Bronx+GTA+05.09.2020+V2.rar/file