This video covers my experience in fixing the chronic lags and eventual crashes that plagued the save game. The fixes are information given on various sources on line and this video is just about my use of these fixes.
Some of the links to sources regarding how to fix crashes.
IGP has a vid on how to fix the game after an update which uses the same solution and some other advice as well (good vid).
Subnautica is developed by Unknown Worlds: