My old save is playable at least. The last really stable Sim Settlements I had personally was 3.1.4. Version 3.1.5 had the empty plots which wouldn't build, 3.1.6 had the plot refresh which would tear down but not rebuild plots, 3.2.0 is fairly stable but still has more CTDs if approaching a large settlement or some cell borders if I go too fast; probably ones with scripts. 3.2.1 is unplayable and I can't even get anywhere in Red Rocket or Sanctuary and I get lots of CTDs just walking around away from settlements. On 3.2.1 I tried setting multithreading to 1 and that didn't help.
I think the comment about how more robust systems have more issues for this may be right. I suspect that the engine overreaches if it thinks it has the resources for Papyrus when it really doesn't somewhere. Setting iMaxAllocatedMemoryBytes too high can actually cause more instability. On 3.2.1 I tried resetting any tweaks, something else people with more memory and processing power probably do, but that didn't help me any. So, number of threads, all those multithreaded settings, etc. were removed and it didn't help. The display settings don't seem to matter as I turned the settings way down and removed all the custom texture packs and that didn't matter. I lowered my
uExterior Cell Buffer back to the default of 47 but that didn't help. I thought it would avoid loading objects for a longer time and they display later but it didn't seem to avoid the issue.
So, I'm not sure what a solution for me would be. Version 3.2.1 seems to be better for most users doesn't it? I tried an abundance of changes to configurations. For now I'm paring down Sanctuary and turning Red Rocket into a spa
I'm relocating the extra people and switching to non-SS power which perhaps contribute less to the build limit.
Were changes made to the global on cell load and unload? Maybe in settlements they should skip some logic? I don't know if the scripting is doing something for the entire settlement each time you cross invisible boundaries within the settlement that it can avoid doing but maybe it's worth looking into.
Also, how does 3.2.1 work for players with many active settlements? I wonder if the number of total plots could be a factor.
Perhaps the cell-change scripting for one cell isn't completing before I enter another cell and I get a CTD from moving too quickly outside of settlements in some locations? One specific place was exiting the Boyston club (BostonCommon02) and turning right (East?) past the park and metro station and continuing straight down the street. That spot always seems to cause a CTD if I head straight down the street too quickly. Maybe someone else can try that same spot because it's really consistent for me. I always collect speed enhancing armor so I may run without sprinting more quickly than most.
Anyway, thanks for all of the suggestions and I truly appreciate the work of Kinggath and his team!