Mine is...varying.
It takes most of my processor with PARTIAL_PRINT:YES:15-and then it maxes out somewhere around 50 FPS. My cap is set at 100, as usual-but I have occasional debilitating freezes (as in "significant mouse lag") while DF figures...something out.
Generally the only thing I have running is Media Player Classic and a couple Explorer windows open in the background-occasionally, organizing my files has helped DF get its head unstuck from its ass.
I have a gig and a half of RAM, a three-gig pagefile, and a Pentium M (a Pentium III on Pentium IV base.)
The problem is, for some reason, DF isn't using all of my processor-it'll go for maybe five to ten minutes, half an hour at most, running smoothly at 50 FPS, and the second I stop paying attention it roughly and abruptly stops for no apparent reason, dragging my computer along with it (despite the fact that the Task Manager insists that only 20% or so of my processor is in use.) At least two or three times now, this has required that I kill the process from the Task Manager, and I've had to hard reset my computer from an apparent lock twice.
I have only about 30 dwarves and 20 animals, most of them exotic-breeding pairs of Warthogs, Black Bears, Grizzlies, and Dogs. I've tried DF Accelerator, but it didn't seem to do much good.