... please by a second 4GB dimm of ram
4GB is VERY low ram today - it could work for GTA V; but you have do close any other programm and disable all services not needed
i think another 4GB would fix many of your problems // have in mind that your dimm has to fit the one built in
also: due to some stuff MS did with Windows now drivers have to speak different to hardware - that resulted in higher ram usage
PC: R7 2700X @PBO + RX 580 4G (1500MHz/2000MHz CL16) + 32G DDR4-3200CL14 + 144hz 1ms FS P + 75hz 1ms FS
Laptop: R5 2500U @30W + RX 560X (1400MHz/1500MHz) + 16G DDR4-2400CL16 + 120Hz 3ms FS