Tile-Based Pathfinding Template problem

I was going to teach someone a few things from this template in the Example Browser (where you lead the chickens past the foxes).

But when I run it, there's a lot of animation and camera stutter. The character has a constant flicker when he moves, as if he's animating at 60fps, and the camera gets knocked around in a jarring way when calling the chickens over.

Is this a result of my browser/machine? Or a common issue with the template?

Just ran this example in my Chrome. I didn't notice anything strange.

Thanks for checking!

I've tested other browsers as well; the walk cycle animation glitch seems to only happen in Firefox.

The camera shudder seems to be based on code, so that's sorted out anyway!