Here's an example of a demo that I think (I wish I had access to an old computer..) is timed much differently in DOSBox than in real DOS. It's the first publicly available thing I tried, since it makes massive use of scroll registers and was very smooth. It's Cronologia by Cascada. There are three download sites on this page:
http://www.mindcandydvd.com/demos
Or, here are three download links expanded (I bought the DVD, so it's okay for me to link, right? 😀):
http://www.mindcandydvd.com/demos/oldskool/Cronologia.zip
ftp://ftp.mindcandydvd.com/pub/MindCandy/Volu … /Cronologia.zip
ftp://ftp.gathering.org/Scene/MindCandy/Volum … /Cronologia.zip
The first site download site worked for me.
Anyway, I remember this as the most silky smooth thing on a 16MHz 386. You'll notice that in DOSBox, the main scroller part at the beginning runs like mad with no speed throttling. In a WinXP dosbox, though it has graphics artifacts and doesn't respond to the ESC key, it runs at the correct speed and you can generally see what's supposed to be happening. If it weren't for this, I'd have thought maybe the demo doesn't contain proper throttling. Strangely, the demo is speed-limited within DOSBox for the non-scroller parts of the demo.
Edit: I just noticed that the credits part (which begins with a bent loop of red vectorbobs) seems to use some horizontal and vertical scrolling for the credits, and is properly timed. It may be interesting to use this part for comparison.
Edit #2: Reposted with a little more info in the Games/Apps thread - Timing issue? - Cronologia by Cascada