Since you have a scene you can do testing with, have you tried turning each figure invisible/visible one at the time or deleting them to see if its a specific figure. I don't only mean V4 or the horses. But also hair, cloth etc.Maybe test it with only one V4 and one horse, maybe that way you can isolate what is causing it.

These are the preview settings I use, you can try to copy them and see if it gets better or whether it makes any difference at all.