Take a look at this post by TheTias. The issue has to do with CASC and how it appends data.
I too have a decent system with m.2 NVME SSD and had annoyingly long load times between acts and reinstalling did seem to help a bit. Still not as good as instant legacy games, but less frustrating.
In terms of dying before the loading finishes, I believe they added a grace period around WPs as a fix in D2R, but then they seem to have used the wrong version as the starting point for a different patch, and we seem to have lost that feature again?