tl;dr at bottom
I started using Sculptris only recently, and quickly ran into the dreaded Runtime Error crashes and it got to the point where I couldn’t even open my model. I’m running an i7-4790k quadcore CPU @ 3.6gHz and an nVidia GeForce GTX 960 SSC 4GB graphics card, with 16gb of RAM. Not the fastest thing out there, but no slouch either. I even reinstalled the program on my SSD, which didn’t help.
Anyway, I couldn’t find anything out there for a fix. I kept plugging away, watching my CPU usage, and noticed it was spiking to 100% every time I performed an action. Being new to 3D sculpting, It took a few hours to realize what the culprit may be, and I figured out that I had way too many triangles. A model with a simple face, hair, and a hood was slaughtering my resources, weighing in at about 2.4 million triangles. I realized the hair and ears were pointless because of the hood, and worse yet I was being very inefficient with my sculpting. For example, I carved an ear (with symmetry) into a globe, and then just shoved it inside my head, leaving a lot of needless clay mass and triangles, so I cut them way down before removing them entirely.
All in all, my model is now sitting at 572k triangles with no visible loss in detail. Now my computer is handling everything nicely again. Obviously as I work on the model, the triangle count will go up, but given that it’s for Dungeons & Dragons miniatures, I’m not too worried about extremely high levels of detail.
So, check your triangle count! Use the reduce brush where you can to remove excess triangles, but keep in mind, this can remove fine detail entirely.
tl;dr: Be more efficient with your sculpting. Keep your triangle count down, and don’t leave needless clay/triangles in your sculpt. THis will get your resource demands under control and should reduce your runtime errors and related crashes.