Just had a tantrum spiral.
My FPS was irritatingly low. So, I made my underground wells into a meeting hall. Once a sufficient number gathered, I proceeded to a channel around the perimeter of the room.
Consequently, the entire floor collapsed into my cistern, resulting in about 20 or so drownings. Of course, some of the drownings took a while. Regrettably, I missed most of the nobles, except for the philosopher.
Undaunted, a created a statue garden that consisted of a floating platform, suspended over the 8 z-level moat. The resulting party, fortunately including the nobles, went on for a season, punctuated with the occasional message that another drunkard has dies after colliding with an object (ie the ground). There are no railings on statue garden. Finally, I removed the single floortile that supported the entire platform. I managed about 30 dwarfs in one go, plus babies. Of course, I have nowhere near sufficient tombs, so the bodies were pretty much left there.
For some time afterwards, I received a stream of tantrum messages. At one point, a dwarf decided to smash the main drawbridge. As a result, the only way in or out of the fortress was to follow the "elven path"--a single-tile pathway studded with upright spikes. Unfortunately, I had no luck in killing the dwarves who I subsequently trapped on the path by extending and retracting the spikes. So, I simply decontructed the supports, killing and badly wounding another ten dwarves.
By this time, there were a half dozed dwarves in the prison--cut off from food and water since some madman destroyed all the bridges across the lower Z-levels of the moat. Okay, maybe not destroyed--maybe deconstructed is a better word. Meanwhile the survivors were regularly going insane and either killing each other, or hurling themsleves into the 14 Z-level chasms that surrounded the main staircase in the fort. By the end, I went from about 140 dwarves to about 20. The only sane ones were the ones in the prison.