Both the update rate of the game and the rates of the animations are currently inconsistent and should be resolved.
This may require significant work to fix, especially the gameplay-rate issues. Ideally, everything should be modified to run at either 60 frames per second, or scaled using delta-timing.
Animations in particular have their own system for scaling to higher framerates, so that shouldn't be as big of an issue.
At any rate, this is a pretty big issue, and it should be resolved eventually.