Well, ok I'll report the most recent one..
Did a displacement test, at 0.2 pixels. Zoomed in pretty close to my plane. So yeah, there's going to be some waiting here I accept that.
Please understand what you are doing here.
You are subdividing a mech down to only 20% of a pixel, then diving it up into triangles for embree and expecting for all that to fit in ram...
Just no way regardless how simple your geometry is.
Show the scene. If you want to subdivide it that far, maybe you mistook blurry displacements with textureftering, when setting up displacement map?
Also, corona does not have out of core rendering, to fully speedup renders utilizing Intel embree. If it doesn't fit in ram, it won't swap like vray back and forth.
It will page to pagefile, lockup and crash.
That is the price you pay for speed. If it doesn't fit into ram, it won't run.
But then again its scene specific like always, provide scene file if you want, many people here will take a look and help.