this is probably happening because you've made a very complex scene, and/or you've got too many apps running, and anim8or isn't getting a fair share of your system resources. if you're running lots of other apps, try closing some of them. if not, you might have to look into simplifying your scene a bit - a good place to start would be to check your models and see if there's anywhere that you could get away with reducing the poly count. high-poly models = more complex scenes = higher system resource (ie. ram, processor time) requirements = slower playback. it can also lag in scene mode if you've got lots of lights.
