I agree with BarelyLegalAlien.
GTA V's recommended requirements are:
CPU: Intel Core i5 3470 @ 3.2GHZ (4 CPUs) / AMD X8 FX-8350 @ 4GHZ (8 CPUs)
RAM: 8 GB (you should upgrade to 8 GB - perfectly fine for any modern games)
OS: Windows 8.1 64 Bit, Windows 8 64 Bit, Windows 7 64 Bit Service Pack 1
Video Card: NVIDIA GeForce GTX 660 2GB / AMD Radeon HD 7870 2GB (your GeForce GTX 750 should be fine if not playing on very high settings)