I've just gotten to the Downtown area in the story after the taxi ride and Rodriguez scene and upon load of the area the frame-rates completely tank to the point of being unplayable. I'm currently running the unofficial patch v10rc3 and I've tried adjusting the audio settings like some have recommended, checking VSync and Anti-aliasing setting in NVIDIA control panel, adding heapsize info to the command line arguments (-heapsize 100000, won't let me go any higher without a memory error), tried setting the executable to run off only one CPU, and nothing seems to work. My current specs are below:

OS = Windows 10 Pro, Build 17134 Update 1803
Graphics Card = GTX 1070
Memory = 32 GB
Processor = i5-6600K

I'm completely at a loss here... I don't know what else to try. Most support topics elsewhere are from many years ago on systems that are much, much older. I'd appreciate any assistance.