Skyrim Project Optimization - Dawnguard.esm Also note that the patches I created myself-DPMO/Weapons and Armor Dragon Priests & Resplendent Racials/VRR/Dwemer Skeleton-have been used before in mod set ups without prior issue-and just be sure I tried it without them and no luck.
The only mods I've used before which could perhaps still be causing it are new versions of College of Winterhold, the v13 Beta of EFF, Death Alternative, or Real Estate. Note that asside from the Faction requirements mods, Dodge Mod, and Thieves Guild Redone, and Cutting room floor, I've used all of these extensively before and never had any problems with them.
Everything has been cleaned by TESVedit (except what shouldn't) and sorted by LOOT. Whichever mod it is, it's causing massive save bloat, making saves reach nearly 30 mb before I can even finish configuring my mods and leave the Alternate Start prison location.