Animated Background Best Practice

Hello everyone, I would like to make a scene with a simple, pixel based, animated background. The animation itself is a tree blowing in the wind. I had considered using a collection of still images to create a basic animation, however I have to wonder if there isn't a more efficient way of handling it. Would sprite style animation (described above) be better than say a movie clip or some other form of animation? Just so we are clear, this is a 2D, looping background that runs in 16:9 aspect ration up to 1920x1080.

Thanks.