Your hardware is extremely limited for newer versions of DF. You can still play, but you need to set a lot of limits.
\data\init\world_gen
medium or smaller world.
CAVERN_LAYER_COUNT:1. Going with 0 (no caverns at all), will give you a little more headroom.
LEVELS_ABOVE_GROUND: fairly few. Try 5 if you have no plans to build high
LEVELS_ABOVE_LAYER_1: 8 or less. Try 5 to start with.
\data\init\init.txt
PRINT_MODE: Try fiddling with these (but don't spend too much time)
G_FPS_CAP: Try 15.
PRIORITY: Avoid fooling with this; it may contribute to system instability or lack of responsiveness (on some machines and OSes)
\data\init\d_init.txt
TEMPERATURE:NO This is a huge FPS drain; temperature is a nice-to-have that you can't afford
WEATHER:NO Smaller benefit, but also smaller downsides
INVADERS:YES Be wiling to turn this off if you really have to
CAVEINS:NO Doesn't help much, but it certainly doesn't hurt
PATH_COST:1:1:5:25 Change the second # from a 2 to a 1. Helps a bit, at least according to some.
POPULATION_CAP:20
BABY_CHILD_CAP:2:10 Limit your population rigorously if you want a decent FPS.
Embarking:
Choose a 2x2 plot, possibly 3x2. No more than 1 water tile (preferably none). Don't choose a spot that's much above the lowest point in the 16x16 embark sector, or you'll end up with more (CUP-draining) rock layers. Don't chose a spot with much in the way of elevation changes, for the same reason.
Gameplay:
Don't hollow out enormous areas (or, if you do, seal them off after you're done with them). Reason: Pathfinding cost increases with accessible area. Burrows might (or might not - haven't studied this in detail) help here.
Replace stairs with ramps. Stairs apparently require more pathfinding calculations.
Keep animal numbers low. Impale pet kittens on repeating spike traps if you have to ... after a few months of coddling their owners with great food/drink/bedrooms!
Avoid keeping too many objects of any sort around (rocks, clothes, kitten skull totems, you name it). Use traders and atom-smashing drawbridge to control the clutter. (make a raiseable bridge; raise it; put a refuse dump under it; dump objects; lower the bridge)
Avoid flowing liquids. You might be able to get away with a small hydraulic project, but always have a way to turn it off.