To be clear, it took me quite a lot of testing to narrow down the issue here, and I'm still not sure exactly where it's happening because I discovered it while running a fairly heavy mod load.

But in my testing, I found that (at least with the mod load I'm using) starting the scenario included with this mod (where a vampire spawns in a coffin) caused the game to permafreeze. Disabling One Big Family eliminated the issue (although there's still a long hitch). I also found that the freeze didn't occur when using any of the other races I have loaded, or when using Prepare Carefully to add a vampire pawn to the standard scenario.

I got this debug log while trying to troubleshoot the problem, and while it doesn't have an error message for what caused the freeze, hopefully it might help to narrow down where this is coming from: https://pastebin.com/Etk2FBXa

Someone managed to actually get an error message to the problem:

Was setting up a modded playthrough, and I too experienced massive freezes when a trade caravan would enter the map and when i first implemented the mod trade caravans that were already there would cease moving and huddle in one spot. Rim of Madness vampires and One Big Family definitely cause conflicts between each other. Anyways great mod, I just wanted to report this bug of sort. Exception ticking hediff (ROM_Vampirism ticksSinceCreation=1) for pawn Raven. Removing hediff.
Exception: System.NullReferenceException: Object reference not set to an instance of an object
at Vampire.HediffVampirism.PostTick () <0x00119>
at (wrapper dynamic-method) Verse.Pawn_HealthTracker.HealthTick_Patch1 (object) <0x001ef>

Okay, so the most likely cause is a wrong mod order. That's as far as I can help you guys. You might wanna look around the help thread on this mod's Discord.