How much more load....Hm. Here's few figures from my experiences that might be helpful:
16x16 12z embark, rocky wasteland on embark: 85 FPS
6x6 147z embark after a year at 18 dwarves, mostly temperate forest: 85 FPS.
16x16 12z embark, terrifying shrubland on embark in rain: 20? FPS.
3x5 130?z embark after 2,5 years with two magma and water rivers and 140? dwarves/visitors: 40 FPS.
aforementioned 6x6 after a year in clearcutting and mass-construction at 60 dwarves: 35 FPS.
3x3 worldgen fortress, 100~ goblins and 500~ elves present on embark: 25 FPS.
3x3 embark, free-pathing 192 strong poultsplosion, 90 strong dogsplosion, swamp: 15 FPS.
The above, chicks caged and dogs walled into a room: 97 FPS.
3x3 embark, 1 pet-forbidden door with few pets locked behind: 7 FPS.
The area all my forts fit into: 2x2 embark.
Lot of FPS load behaviours stack, tbh.
- Clutter by itself impacts FPS, but for every stone to consider for a job, for each job it has to look through each stone. Caravan arriving on map can give a slump.
- Pathfinding can get lost in big open spaces like sky, which scales with embark. You can run around fine at 100, and then pack of flying nasties from below can quarter your FPS.
- Each creature has their own timer and job check. But when it comes to pathing, each creature has to path around all the creatures in its' path.
- The more things it has to decide to render on display, the more resource that uses up. You can lose third of your FPS by viewing the surface level on areas with vegetation, and I've heard of threefold difference between small and maximized windows for a certain setup.