Im seriously beginning to hate my dwarves for claiming clothes and never wearing them! It's so frustrating! I had a good sized gobbo siege hit my fort, and i survived, but sadly my FPS did not. Before this particular siege, I had about 30 FPS, which wasnt great but I was doing well managing with it. After the siege now a whole season later, I have only 11 FPS, the only that changed in my fort in this time in a major way was I now around 500 new items of clothing (in addition to clothes claimed in past seiges) my dwarves have claimed laying on my battlefield I can do nothing about. I really hate this issue especially since it seems to be killing my FPS so much.
Just for info, I've been doing what I can to keep my FPS high since the start of this. I've turned off temperature the whole time. I capped my dwarves at 100 and my children at 15. right now, I have 105 dwarves, the most I ever had was 108. I've not broken into any cavern layers yet, although I have reached the magma sea since practically the beginning of my fort. To do this, on my embark I dug down to the magma sea, then made a note of the z levels that my caverns were on, so I wouldn't open them up until I was ready and use up any FPS, i then reloaded the map knowing what to do to avoid the caverns. I've been using multiple dump sites thinking it may increase FPS, for instance my refuse and corpse stockpiles were getting huge after many gobbo sieges, so i made a dump beside my refuse pit and dumped alot of the gobbo bones and bodies there. I also put some beds and coffins in one of my dumps because I accidentally made too many early on in my fort.
Also each time I did any exploratory mining for stones and ores, I walled off the entrances after I finished so my dwarves wouldnt needlessly pathfind that z-level.
So after all this effort I've put into trying to keep my FPS at a nice playable level. I'm quite angry my FPS drops from 30 to 10FPS when it seems the only thing different it a ridiculous amount of newly claimed clothes scattered across my battlefield.
I really think this could be changed easily, for example one way is just allowing claimed items to be dumped instead of laying there unused.
Second, maybe make a incinerator type job available, there a player could incinerate items they didn't want taking up space anymore. The job could require a constant supply of charcoal, coke, or magma as fuel to get the job done.
I hate when I see this issue on the bug report it is listed as minor. I understand it takes a few years before the dwarves clothes start to wear out and they claim new ones. But boy, once they do start to claim clothes a lot of problems begin to occur. Claimed clothes never being able to be dumped or stockpiled, clothing shops becoming cluttered, significant FPS drops, etc.