I went through the same process you did. What helped me in the end was running the game through Vulkan instead of DX11. It currently runs fine. Which is funny because pre-patch 2 it was laggy as hell on Vulkan, unplayable. And I swear I tried it several times post-patch 2. But it suddenly started working for me... also if you are running the game through GOG Galaxy, you could try rollback to previous patches, although this did not help me. This game behaves really weird and I personally think it is still Early Access, not matter what the devs and magazines say. And will be for a long time.
You either have to keep trying or wait 2 or so years until the game is really finished and then play.
