Bahahah, alright... that's hysterical. I don't think I'd ever seen this.
For reference, my machine runs this at about 45 FPS. That's a pretty damned good rate in general, actually. However, there are some things you might do.
I take back what I said about the outdoors. You don't have an inner area helping to control the flood pathing. You've... cripes, you've walled in the outdoors.
Use Traffic Pathing to remove the water-walls from even being part of the selection except when you need someone out there. Same for the pigpens.
You shouldn't have significant flow problems now that you've closed the drain's floodgates. You just need to wait for evaporation on what's left.
Your digs belowground are all massive squares. There's no walls to help control pathing, there's no traffic areas to help keep dwarves on the straight and narrow. Level 135 alone is probably chewing up horrendous amounts of FPS. Here's a great example. Your Dining Hall is about 45 x 25. The pathing to get into it isn't so bad (it's near central stairs) but that's just HUGE. Also, you don't need to keep your booze there, just food nearby. Booze is drank where it lies.
Your stockpiles are monstrous, and in the center of the room, causing everyone who wants to do something past it to have to path over a 15x15 stockpile, sometimes twice. A hallway next to it with walls and a little selective traffic controls would do wonders.
Level 115 is a perfect example of where to drop some spare walls and heavy restrictions. The burial grounds don't need anyone to path there except when they're buring someone. d-o-r the entire north half. Wall up the entry to the south half until you need that space, to remove it completely from the algorithm.
Cavern 1 (114) is pretty open. There's just not much to do about that, but you could wall up the northern exploratory tunnel and remove that from the pathfinder. You might also think about locking the hatches when you don't have anything down there you want done. Although, I have to ask... what's with the thousand doors of doom?
In general though this doesn't look too bad, just some minor tweaks. Your flows are controlled and I think you'll get a bit better when the water finishes evaporating. Seal up your exploratory tunnels, get some traffic controls going for your massive stockpiles and upstairs areas, and you should see some improvements.
On a side note, anytime I need a stockpile larger than 10x10 (except for barrelled items) I quantum stockpile the results. I also like to build supply stockpiles above/below the workshops with direct access stairways, so the only people who need to path through that space are the ones doing work in the workshops themselves.