I think it's actually a timer problem in DBPro (I got the FPS using Fraps). The manual states that the framerate system is based on milliseconds and isn't accurate, but it relies on smoothness. Makes sense, because setting the framerate to cap at 60 actually makes it cap at 66 unless you're running in a full-screen mode and your video settings have the monitor refreshing at 60 hz (Which I always use).
A thing I've noticed early on, the pyramid model doesn't seem to be complete. When you drop through the hole, you end up inside the model and can walk back out through the invisible sides of the walls (Although you probably already know this).
I haven't played the original DaggerFall so I don't know what kind of gameplay you're aiming for... well, good luck on this project.
Edit: Another suggestion I would like to make is that the wind speed changes too rapidly for the snow effect. I think you should make it more constant.
Edit #2: I almost forgot that there is another graphic glitch in this game. When you have the camera at certain angles, there is a white vertical line on the screen, but I can't imagine why it appears like that. Is that something you can look into by any chance?
HP Pavilion | Intel Pentium 4 CPU 2.40 GHz
512 MB Ram | NVIDIA GeForceFX 5600 AGP, with 256 MB Ram