Hugely interesting thread. Have been having the same issues back in 2015/2016. Good to see my suspicions were true then. I am testing out the new Unique NPCs mod made by one of these guys in this thread after he redesigned it but I still get the lag spikes unfortunatly. But this might be on me since I might have made some errors during the FOMOD installation and/ or have double mods loading. Will be testing some more. If you manage to get Unique NPCs to work without lag spikes you could delete all the NPC instances in Raider Overhaul so you can have both. Cheers to all the modders and investigators over here, keep it up!