NOTE: I got 150, as stated before, on a laptop with 1.86 GHz, 1526 RAM and is a Vista. So its not impossible. Just don't ever expect to get a King before going mad.
I would like to see you play and take on HFS and win with that FPS number too. I got as far as getting a king on a similar computer setup (not FPS), but hitting 0-1 FPS no matter what I do kinda eats my will to continue.
For HFS, set the
in the world generation to zero. That will eliminate lag when you breach.
Also, use a small map. A 17x257 map runs faster and saves quicker then a 257x257 map, and it pretty much has the same stuff on it. Likewise, a 17x17 map will be fastest across the board.
Butcher all cats. If the have been adopted, kill them. If needed, kill the owner.
Use smaller embark areas. A 6x6 area has something on a thousand times the space of the full 2d map from way back when. Go 3x3. There is almost nothing that can't be built in that size map.
Smooth your stone and set up dedicated cleaners. There is speculation that dwarves clean up near meeting halls, so use them to hit dirty spots. Set up a bath for your dwarves between the dining room and the meeting hall, or other path every dwarf walks. A 2 deep chunk of water will clean your dwarves nicely.
Set you cap to 100 and the child cap to zero.
Invest in more ram. DF can eat up a ton of ram space.
Turn off cave ins.