Not a fix, but have you considered making a low-ish quality render instead?
Interior renders take a bit longer than exterior renders for us, but we just have these running in the background while we do other things and still keep the render times around max 15 minutes (depending on the surface settings) for a 195x135 mm picture at 300 dpi.
We make another seperate render for ambient occlusion to make things look a bit better in post production, but since you don't get those from the 'screenshot' method you are using now, you might not want / need that.
Attached example took 30 minutes due to the water surface taking up more calculation time (it is a house-boat project), but generally speaking if you have a lot of 'flat colour' surfaces and maybe a few wood grains, it shouldn't take too long.
Erwin Edel, Project Lead, Leloup Architecten
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