I was so slow because I was hauling a bunch of severed heads and bodyparts to make an undead army from. I resurrected them all and survived, but I had to leave the area because there were literal hundreds of elves coming in and it started to seriously lag the game. I think about forty or fifty of them died, but I did not count.
I've been assassinating powerful historical figures and dragging them back to my base in a frozen wasteland. I call it the "corpse library", because it looks a little like a library. As you can see, I have already begun the assembling of my army. I chose to build it in a frozen area adjacent to a wasteland so that the bodies would perhaps preserve a little longer.
The room on the bottom right is a freezer, exposed to the elements for maximum chill. It's to store trophies, bodies which are too irrelevant for a shelf, and planned weapons. For instance, there is a huge polar bear population in the wasteland just west of me. I intend to fill backpacks full of their severed heads and give them to a companion, as a kind of undead suicide bomb.
The room left of the freezer is for historical figures which are large and imposing enough to face a real threat as zombies. So far, it's just night creatures, but I know of a location where a dead titan is, and I intend to bring the body back with me.
The room that I am in is intended for historical figures which have enough relevance for their corpses to be stored, but may not be physically large enough to truly become powerful undead slaves. So far, I have killed few worthy of my criteria. The only one who fit was an elf-turned-goblin who was responsible for tens of murders and hundreds of babysnatchings before joining back with his elven civ, but I threw his body into a volcano after I killed him by gouging his face off and breaking his neck, for stealing my (now undead) companion's only child.
The room to the right of me, above the freezer, is just a shelf for bodies with no historical relevance but statures which make them very useful to the army. I intend to travel to the ocean and kill whales to bring them back to the shelf. If I can find elephants or giant creatures, they will also be put there.
When I am done assembling my army, I will pay a tomb a visit for the sake of getting some meatshields, then I will track down the elven armies and give them the fight they deserve.