The author has stated right below that some animations can be improved. Make your suggestions.

The author is on HN and commenting in this thread. So I did make my suggestions: Make the animations shorter, more subtle.

Hello, thanks. I see lot of people would prefer what you're asking, and actually the Material Design specs are not followed very well by me regarding the animations. If you'd be so kind to open an issue on the GitHub page I'll be happy to assign a priority to it and work on it when I find some time.