Hi folks,
I was really happy, that some demanding (related to surface details) scenes stopped crashing upgrading from 4.7 -> 4.8 -> 4.9.2.70 -> 4.9.3.166.
But now I used an asset with tires. To show the real 3dimensional structure of the profile, it was necessary to apply some Displacement Dub-D. With DAZ 4.9.2.70 that worked pretty well to show the details.
Now I tried exactly the same with 4.9.3.166. -> Desaterous !!!
As we all know, there are some situations, where we need way more as only bump/normal. Up to 4.9.2 Displacement worked very well.
In the current test Displacement SubD is set to 4. Rendering with 4.9.2 you see the well defined profile. For 4.9.3 there is only a smll hint of what the structure could be.
And even worse: Increasing of Displacement SubD didn't show any improvement. Contrary - even Displacement SubD = 2 shows exactly the same resolution. With SubD=0 the tires are without any surface detail (asolutely round and smooth).
I just was on my way to upgrade to 4.9.3. But luckyly I stopped really in time. 
Hello Folks / DAZ-Devs: Here really is a construction site !!