I haven't had any crashes, but I do notice the CPU activity jumps quite a bit in the material room, and then -- more importantly -- never comes back down until I restart Poser. It stays around 15% even when Poser is sitting idle for long periods of time. You can hear the fan spin up, makes it hard to tell when renders are done (normally the fan slowing back down is my cue).

I don't use "enable hardware shading" because those previews aren't useful. All the cycles shaders just turn uselessly white. With hardware shading off, if there is also a firefly texture, the preview shows that instead so I actually have something to work with. As discussed here.