Well, this isn't very brief, but I used a laptop from 2009 until recently, so I've experimented a lot.
- Temperature cannot be over-emphasized. If you play with temperature, avoid lava and anything else that's really hot. (On a recent fort, in the aftermath of a medium-sized lava/fire incident, my FPS was half of what it used to be. From 100. Turning temperature off fixed it, and the modding world helped me out with making magma deadly again: http://www.bay12forums.com/smf/index.php?topic=142020.0 .)
- The population cap is the other huge one.
- Traffic designations give me a good 10 FPS back sometimes, and fort design is as important.
- Don't designate large areas for smoothing/engraving (I think Toady fixed that in the newer versions.)
- If your dwarves use the caverns, set the caverns to high openness (and low something else...density?) in worldgen.
- Use minecarts for long-distance transport, especially heavy things (that's more like making your fort feel speedier at any FPS.)
- DFHack's clothing confiscation and cleaning commands can help a little in oldish forts, if you aren't opposed to that.
Major (but game-changing) strategies: avoid liquids and excessive invaders. If you've just got yourself sealed in, the invaders don't matter anyway. Disabling them would be a drastic measure.
- Avoid water on your site, including rivers, lakes, and oceans
- Avoid evil regions and necromancer towers (because undead pathing is kind of wonky, undead have a tendency to multiply, and thralls love to wrestle very rapidly forever.) Embarking on an island would keep the armies away, but still (I think) allow the various beasts to reach you.
- Giving invaders a target to path towards can help. I noticed that after the undead horde outside killed off the last animals, my FPS dropped by ~30. Read: fight invaders instead of waiting them out.
On the hardware side, if you use a laptop, keep it cool! Otherwise, the CPU usage of DF will be sharply limited, to keep you from melting your PC. Single-threading in a world of multi-threaded processors exacerbates the problem. If you use a desktop with multiple cores, try using Task Manager to shove everything else off of one core's threads, so DF has it all to itself. (Then anything else running won't infringe on DF's territory, so you can do some things in the background.)
As a last resort, you can always make fastdorfs.
Hope it helps! I love DF, but it's not computer-friendly.