Well, a while ago I decided it would be cool if the sunrise and sunset times changed according to the time of year. Realising I hadn't the faintest idea how to make this happen, I compromised and decided to just edit the ini file every in-game month. When I set the sunrise and sunset times too close together, however, the sun zooms across the sky at a ridiculous speed and looks incredibly stupid, particularly with real time shadows. I was wondering if it's possible to alter the path of the sun, so that, say, it only climbs half-way to the zenith of the sky before beginning to set again. Or is this hard-coded into the game?

I think it is hardcoded. You could lower timescale to reduce sun/shadows speed though