Soo bad. I have a huge problem in 10.14 and perhaps 10.13 ( I don't remember if I ever used 10.13 but in my test I have same problem in 10.13 ) So I imagine that in 10.12 it is ok.
I have noise in reflection and refraction. See pict, this is DENOISED BEAUTY, in 10.14 there is an ugly noise especially in dark areas.
Any idea ? Something wrong from my side ?
I don't know if this is your case, but keep in mind Octane Light and Octane Light Vectron used together could cause noise unless you adjust sampling rate.
In architectural renderings you could try using fake glass material.