Aircraft Stutter

I've noticed a lot of air units that flicker, stutter, or skip when they make a pass. This is especially true of user-made air units. The animations themselves are fine, and the effect does not consistently happen every time they run. I've been experimenting with very long (5 second) air animations so that the air unit can run a single animation when flying and not repeat, but the flicker may or may not happen despite the size or length of the animation. Does anyone have any experience with this or know what is causing it?

As an add-on...I've consistently found that the game won't play longer animations, but only the first half second or so (except for death animations). Right now I think this is the cause of the skip. Firaxis animations run under half a second and have very few frames.

When I was running Civ 3 on my previous not-very-powerful computer the game did not play long animations for air units. With a new computer I don't have that problem anymore. However I am noticing something similar to what you describe with variable geometry wing aircraft. It seems that during the run the game sometimes actually shows: Run (wings in one position)/Default (different position)/Run...