I've lucked out, really. I can run just fine, now that it's full screen. The issue appears to be completely gone.
Tomorrow, I have a full day to myself. Planning a very dwarvish trap building binge. My second idea-from-the-powers-that-be has already struck.
Currently under construction is "Trapnest, death of the gods". I do not yet have a source of good metal. However, by forcing my carpenter to run around the clock creating wooden spiked balls, he has quickly become legendary and is churning out these implements at delightfully horrifying speed. My tunnel down is already ringed with traps. My corridors are being outfitted now. I shall fear no crazed dwarf. My fortress shall be self-culling, if not self-cleaning.
Once I get my layers sorted out, and start a mine-deeper shaft, I plan on utilizing a death bridge. The idea being that I'll have a bridge about 50 paces long, one pace wide, and with traps the entire length. On either side, a drop three to five paces down. And down there? Each delectable square will be bristling with my legendary carpenter's spikes.
I know now that not all enemies will be caught by them. However, I do have the impression that even those that might ignore or dodge them cannot do so at full speed. My primary military force will be crossbowmen.
I look forward to tomorrow to see how it pans out.