I have 8GB RAM and 2GB VRAM. Only 4GB of RAM and 0.5GM VRAM are used. Nevertheless the scrolling is more fluid when disabling texture streaming in the ini. At least that's my subjective impression...
EoCApp.exe is a 32-bit process so can only access 4GB on a 64-bit system (and is limited to 2-3GB on 32-bit - I see 1.6GB usage myself). If you want to throw more memory at D:OS, you might want to consider copying the Data subfolder to a ramdisk (it is constantly read as the game runs).
However given that folder is 11GB+ in size, a more practical option might be to copy just the main .pak files to a ramdisk and use
Link Shell Extension to hardlink them back to their original locations.
