If you dislike them, you can disable those kinds of animations by toggling `toolkit.cosmeticAnimations.enabled` in `about:config`
There's a big scary warning about making any changes in about:config, so I'm reluctant to do so.
Changing a single about:config setting is pretty harmless (you can just reverse the process if you need to), and callahad is a Mozilla employee. You can do it without worry.