Maybe... being walled in makes for quicker pathfinding? Are you having a 2x2, 3x3 or 4x4 embark? How many idlers?
hm, being walled is not only thing there, imo. i am using 3x3 embark, always(but it did not helped me with fps in earlier df versions)..
restricting used area on map by walls may have its effect too, but since dwarves are not puking everywhere now(as it was in 0.28's) i tend to use overground terrain as part of natural caves(i hope you know what i mean) - i.e. for storage.
life area is quite dense, and typical - but i started to use 3-tile-wide main corridors and it HAD significant effect. for rarely used corridors 2-wide-tile space is used.
Do you have drawbridges as big huge actually-lockable door?
2 tiles wide bridges ONLY with 2 doors on its end. doors still can be destroyed, but it gives time to draw a bridge - and here's weirdness of civs that can swim: although such beings thrown to the pit can swim and get out off water easily, they NEVER swim across water to reach NOT LOCKED doors. They search for way for EXIT only, if they're in water. they do not swim through water to reach fort as it was seen in 0.28's.
btw, i will post sshot to visualize how entrances are made now in few minutes..
How many cage traps do you use?
Far less, than in 0.28's, 90% of civs can avoid traps, so it is useless now. just 2 tile long area at every entrance + 1-2 inside, AND some at pit/dump corridor(disarmed enemies are tending to break free what is quite enterntaining, but usually end in trap then).
I am using these cagetraps for getting elephants/animals mainly. They tend to stay close to such entrances for weird reasons...so usually cages are full in no time.
Do you open up the caverns for wood and plant-gathering and hunting?
as i said earlier, never; my method is different - i am just walling open area and it is becoming part of fort then, it's area adjacent to main entrances, roof is max 3 lvls over entrance. i do not like to change overground areas, i am just adapting it, so my fort is like melted into natural landscape, usually.
btw, hunting NEVER occurs in walled out area(not sure, if NEVER, if area is not under roof, but NEVER under roof, i am sure of it).
Elephants... do they have 4-8 babies per year?
i did not check this to determine how much, but imo, too much - i have gigantic amounts of meat now + fat( :E) and really, if only weight wasnt a problem for caravanas, i could easily buy EVERYTHING that comes with them just by selling that meat..
Capturing and taming wild animals is plentiful meat too, or breeding cows and pigs. Actually rabbits should become adult in half a year but that's not possible in DF. Minor bug that animals don't need to eat, and dwarves eat very little.
To be honest i stopped care even for dogs, since elephants are so easy to..be,hm, obtained. I saw what elephant is able to do with unarmed dwarf, so all grownups are ending as war machines, restrained at entrances, just for additional safety.
I am killing everything to control animal amount, but damn, how to sell all that food - i am afraid that EVERY butcher action is closing me to less fps just because of gigantic food amount and rising barrels amount...
ALSO - atom smasher is NOT eliminating clutter, imo, so it is not method for getting rid of it...it just takes it from sight, imho(ZERO fps effect, regardless of how many things i smash there...).
Sorry for engrish, again..
btw... after another dozen of hours i am noticing fps drop now... i am not allowing to get out off fort to anybody now(it is REALLY dangerous now outside, in 7th year), so massive amount of dead bodies and equipment is everywhere now(as these stupid invaders are fighting with each other and with megabeasts too - one of MB's killed c.a. 40 invaders lately, what a mess, lol, goddamn beast did not want do be drown
ed :E)...i assume, that main problem now is not pathfinding, but items amount AND maybe, i dont know, some buffers are not cleared in time after sieges?
upd2: i just got ambush and liaison - fps dropped from 78 to 35 OMFG :E