You should Zremesh some parts for more performance, or use the decimation master. It allows you to mantain the details and less polycounts. As m4dcow says, 116 million polys are too much in a model.
M4dcow's probably on the right track with the data writing. Optimizing your mesh or just handling smaller details in a detail overlay is probably better than having that all in your sculpt. Have you tried moving the Scratch Disk path for ZBrush? It defaults to your MyDocuments/Pixologic folder or something like that on the…