CPU & FPS
Meta-post from lurker: Remember that it's the programmer's responsibility to consider if an idea is possible given the limits of technology available. It's very easy for Toady to decide if something will be unworkable, because he knows everything that goes into his game, down to each function call for each object.
This bothers me for most games with areas for suggestions in their community - It's ok to take established performance or technical difficulties into consideration when making your own suggestions (though sometimes you might be limiting yourself this way), but I've found repeatedly that shooting down ideas of others for that reason tends to be non-productive. It can force the other person to take a defensive, instead of creative stance, and turn others that might not have a full picture of the issue against them, so that their idea gets pushed down where the developer cannot see it.
Especially in a forum format, it can serve to make threads disappear into the archives where Toady is more likely to not notice it - if something is unworkable, he can step in and say so if he wants. But otherwise, unless the idea is for a technical solution to current issues rather than a creative addition to the game, or the devs have said specifically that additions to that area will likely not be put in until a technical solution is found, IMHO it's better to keep the creativity flowing.
OT: Abandoned demonic ruins, where brief surges of order were suffused with the chaos of death and mischief, subsequently left for your dwarves to exploit if they can dare its descendents. Lots of broken arches, crude engravings, and temples to dark forces, etc. Pathetic, easily-dispached starving proto-goblin servants lurking in the shadows to go with.