GTA 4 FPS
I don't know of any official mod that boosts FPS in GTA 4. You might find third-party tools or hacks, but they can affect game stability.
Consider adjusting the settings? GTA 4 is why I'm excited about GTA 5. The frame rate across all systems is terrible.
Playing GTA 4 on PC is bad regardless of your system specs.
GTA 4 won’t run well on your PC.
It simply doesn't work well as it is.
Adjust the parameters until you achieve the target frame rate.