I am cutting down every tree I can see on the map, and now it seems fps has increased a bit, or perhaps it is just my imagination?
Leaves falling and growing fruit (not to mention it rotting/hanging around as cluttering floor stuff for ages) does not help FPS any more than calculating changes like having to grow all the trees and have them grow 1 z level or 2 z levels taller each milestone birthday (most 4x4 trunked trees are 50+ to 100+ years old, high woods particularly in arena mode take a long time). Process all those logs into goods and ash or quantum stockpile the lot i say, phooey with elves, and when you get bored/tired/run out of trees on the surface, cut all the ones down underground too.
Good reason to start in a desert. Though the flames engulfing my caverns were not by design. Probably not helping FPS issues either.
As an addendum to my prior goblin-elf attack post, I found some body parts of one of the elves. On a 5 urists-high wall, behind fortifications. About 20 tiles away from where most of the body was. Maybe 25 from the furthest chunk.
Someone hit a homerun using an elf-ball.