Choppy and laggy horse riding

Whenever I ride a horse it runs extremley choppy and laggy. The thing is that Minecraft still runs stable when the horse lags. Here's a video showing the problem: (I used AMPLIFIED generation in that world, but the same thing happens on all world types)

http://www.youtube.com/watch?v=pIbY978bQN0

My framerate remains high and nothing else freezes. I've been experiencing this since the release of horses. This happens in all the gamemodes.