Zremesher 3.0 freezes completely even with simple few million polygon models. I have i7 5820 with 32gb mem and win10 rig.
What could cause this behaviour?
A “few million” polygons, while easy to sculpt on in ZB, is not necessarily simple for Zremesher. It doesn’t crunch higher polycounts as well as dynamesher, or Decimation. It does better with low-medium poly objects. There could also be something problematic with your mesh topology giving it trouble (for instance, it doesn’t like the kind of “smashed” topology generated by the clip brush).
Try ZRemeshing simpler low poly object, like the polyshphere in lightbox > tools. If that works easily, then you probably need to reduce polycount or otherwise simplify your target subtool. Reduce subd level first if applicable, or send it through dynamesh at a lower res. Make sure to duplicate the subtool first so you can project any lost detail from the original onto the new mesh.
If there’s still some sort of freeze or hang Zremeshing a low-medium poly polyshere, then there may be an issue with your zbrush installation.