Bah! Fire the thing up in the vanilla settings.
If it runs smoothy: Rock on!
If it runs too slow, turn off weather and temperature. This'll make the game run much faster, at the expense of dwarves being able to swim in magma, and water never freezing/thawing.
If the game runs fine until the population reaches a certain point, and then slows to a crawl, designate your major hallways, trail and roads as high traffic areas. This lowers the CPU cost of most pathfinding considerably.
Building a cage building and stuffing all your extra critters into it helps cut down on pathfinding a lot, too. They just wander around anyway.
--and people who are afraid of spiders are never funny.
--unless you carve pictures of them, surrounded by giant, venomous, cave spiders, on the walls of their bedroom. Then, they are hilarious.
