Regarding your suggested settings - the right settings depend on many things.

But for speedy test renders those are horrible.

Make the following changes to speed things up until you're ready to do a final render.

Subsurface Scattering: Off

Raytrace bounces: 1

Irradiance caching: 30

Pixel Samples: 1

Min shading rate: 1

Using the settings you had my test render was 97 seconds. After these changes it was 7 seconds.

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Renderosity forum reply notifications are wonky. If I read a follow-up in a thread, but I don't myself reply, then notifications no longer happen AT ALL on that thread. So if I seem to be ignoring a question, that's why. (Updated September 23, 2019)