For animation, I usually put in a change and frame rate cap. High frame rates are only allowed if there is very little change between each frame. If there's a lot of change, the frame rate has to be almost bottomed out, once every 10 seconds or something if there's a lot of change, though this depends on the size of the image itself. Then again, you wouldn't want my record-holder posted here - 3444 frames at typically 10 fps, 4.1 MB, over 8 minutes long, needs ~150 MB of memory (!), and has a 320x240 image size.... Don't believe I have something like that?
Here's proof. It took only 7 days to do it, 3 to make the scenery, 2 more to make the position notes for how it'll behave, another for processing, and the last for testing. Scaling it down to 80x60 won't do much good....
Edit: 150 MB of memory - just checked it.