Thanks for the tips 
I was about to build the scene with NumHemisphereSamplesScale > 400 at Medium quality, but I notice that the build time was incredibly slow, so I guess I’ll try a lower value for that.
@: based on Rafareis reply and by some tests the scale is what gives you the soft shadow details from large/small objects and it makes quite the difference, and of course it increase the build time, not entirely sure how much since I mixed the values between tests.
With 0.15/0.25 the shadows quality is really good, but the value also depends on the scene itself and the degree of detail you want.
@: Are portals going to be included in a release soon? 