Has anyone else problems with the "Display Render" in the Viewport - when using NVIDIA Iray (not Filament), it's like it freeze even when doing simple scenes, a posing character and hair 🙁 it's sooo slow, and you are in doubt whether DS is about to crash. Anyone knows how to change/fix this, via the Preferences settings. It's like it runs short of RAM.
If it gets slow then in most cases it's the CPU fallback of iray, means your scene is to big for your VRAM. Install afterburner and check your VRAM and GPU utilization ...
I checked the Render Settings/Hardware, and for some reason the CPU Thread Affinity (whatever that means?) - was unchecked! After checking, DS runs better/more stable, in Viewport/Iray mode.