Anyways, the gif is now removed. I hope the performance gets much better now. The CPU fans on macbooks going up where probably due to a lack of a dedicated graphics card. This happened to me with my macbook and large gifs too.
If the problems don't go away, please create an issue in the repo so we can work on improving this! It would be important to include your steps so we are able to reproduce these issues.
edit://
Since this comment is on the top, I'll address a few more questions here too. If you missed the demo, it's here: http://editor.ory.am/
First, this is a layout editor first- and foremost. Behind the scenes, React, Redux and slate.js ( http://slatejs.org/ ) is being used. Each cell is a React component that you can implement yourself. In fact, the text component itself is a plugin that wraps slate.js.
Second, we're integrating this editor in Germany's largest e-learning platform (wiki-esque) with ~1 million MAUs: https://de.serlo.org
And lastly we're working on a business model behind it, with our ory sites product (early access): http://ory.am/sites/
If you want to check out our other open source products, feel free to do so: https://github.com/ory