To fix the notorious stuttering and performance issues inherent to the original PC port, it is highly recommended to use DXVK, which translates the game's DirectX 9 calls to Vulkan.
While Steam and the Rockstar Launcher provide the "Complete Edition" (v1.2.0.43+), many enthusiasts prefer the patch due to its superior compatibility with iconic mods and better stability under certain conditions.
Grand Theft Auto IV remains one of the most atmospheric entries in the franchise, but it is notorious for its poor optimization on PC. If you are running an NVIDIA GTX 1070, you have more than enough power to run the game, but the vanilla version often struggles with texture popping, stuttering, and poor memory management.
: Bundle d3d9.dll files from DXVK to eliminate the "stuttering" inherent to the original PC port.