Blender =/= Cycles, there's are other options for rendering in blender that are more focused on accuracy than speed.

I personally use LuxCore for 99% of my work as it's an accurate renderer that's still easy to use. If you're interested in more hardcore physical stimulation there are various flavors of Mitsuba available and Appleseed is also worth a. mention even though there isn't a current blender plugin IIRC.