Maybe I'm just getting old, but I found most of the animations in this article to go too fast. I couldn't tell what was happening, couldn't tell what I was supposed to be looking at.
It's not that you're getting old and it's not that it's "too fast". The problem with many animations like this and why they make no sense whatsoever is because they cycle without adding a little pause... So you have no way to know when it's beginning and when it's ending. It's endemic on Github.
Some .gif files are properly done but IMO most don't explain anything, only add confusion and would be better served by three or four screenshots.
There are poor UX and then there are these kind of cycling .gif files.
An animation that shows a very slow pace might communicate that the tool is slow too.
1) list of text 2) input to filter the list down. see: list gets tinier