My only things I can think of to optimize to get anywhere close to 1/10th of this:
1.Advanced parameters
1a. Make it a pocket sized world as small as possible with the entire environment regions that dwarves can't normally inhabit like deserts
1b. Allow one dwarven civ allowed and no others. No megabeasts or anything either and you'll only have the dwarven capital city spawn and nothing else
1c. Turn off cavern levels, hfs, etc as they clutter the map with creatures and fps drags
2. I'd embark on a slightly smaller setting, but not too small otherwise you can't fit the dwarves to come. If possible I'd pick a mirthful biome. The sunshine alcohol seems to be good at pacifying dwarves in my own notes, but any biome will do
3.Pick either the surface level or the dirt level immediately below it and plan to convert it into a massive farm that'll use most of the map
4. Cut down on traffic through a caste system. Farmers only farm, for example, and they're trapped in their own area so they can't even potentially path around.
5.Use legends viewer and identify if there's any towers, werebeasts or vampires. If there's a tower you're gonna wanna wipe them out for fps and take their books
6.Incrementally convert dwarves to the immortal class in question and imprison them in squares where they can go helplessly mad.
7.Maintain a "pure" dwarf social class that exists solely for breeding and enjoying alcohol and prepared meals in a small area. Just enough space to fulfill needs and you can convert off spring who aren't going to continue in the breeding program into immortal prisoners
Rack up the years as your prison-paradise slowly expands to the bottom of the earth uninterrupted by monsters or caves. Soon enough your caste system will become obsolete as you only need a class to produce food and alcohol and another to consume and mate. And as you identify your mating class and optimize their time you can eventually balance them with the producer class and just outright remove one of those classes and imprison them as immortals leaving you with a small number of dwarves that actually move and reproduce(who are later imprisoned as they age too much with one of their descendants taking over)
EDIT: Tbh if they're in 1x1 prisons you can have an extra small map that extends to the bottom of the earth. No caverns so it's just straight stone that is easy to carve in a way that is efficient