I think I may have solved the crash to desktop issue I have been seeing. It's not an answer people will like to hear, but I will just have another session to confirm the crash no longer happens and post back.
Edit*
I've been doing extensive testing (pulled an all nighter) and here's what I've found as have tried many things people have been suggesting all over the internet the last 9 hours or so.
1: Changing the DLSS dll file to the previous version 3.1.1 might solve crashing -
It did not.
2: Using FSR on an Nvidia card might solve the crashing -
It did not.
3: Using an older Nvidia driver might solve crashing -
It did not, back to 543.31 Studio.
4a: Replacing the oo2core_9_win64.dll that the game ships with using a previous version might solve the crashing due to a memory leak known in the shipped version -
It did not.
4b: Using the older dll will also fix the loading time and shader comp time -
It did not, still 23 mins to shader comp on my system, and still 40-56 seconds to load back into my save state.
5: Lowering VRAM usage by lowering settings might solve the crashing -
It did not.
In the end what i found to completely fix the crash to desktop for me is to not use FSR or DLSS at all. Granted with them off the fps is 20fps or more lower, but at native 3440x1440 y 3080 Ti is able to keep the fps at above 60 anyway, and I have Gsync to sort the motion smoothness etc out as well which works very well here.
So yeah, for now if you have the crash to desktop issue like I did, then simply turn off DLSS/FSR and run native until the devs release a patch to fix whatever is causing all this.
And because I am not using DLSS any more, I have had to
lower the first two Texture quality settings from Ultra to High (hard to tell the difference between them too). All other settings are on Ultra apart from the usual naff stuff which are off (Motion blur, chromatic aberration, depth of field minimised etc).
This is probably not what people with 10GB or less VRAM cards want to hear, especially anything below a 3080 class because the fps will be much lower still, and a such those folks will have to lower even more settings until a patch is out that fixes the crashing.
My issue specifically related to crashing to desktop, I have no stuttering or anything like that.