The animation of vertical tab is very stiff. When the mouse moves over it, it delays for a while before expanding or constracting. And there is no animation for the contraction process when the mouse is moved away.
Firefox has a third-party vertical tab project inspired by Edge, using user stylesheet and addon. Its animations are implemented in css and the experience is much better than Edge.
The difference is clearly seen in the GIFs:
Why it should respond immediately:
Its delayed expansion is not enough for me to click on a tab, which means that it will expand when the mouse is about to leave, even if I don't need to expand it. So the reason for the delay can't be to quickly switch tabs. So, why not respond immediately? Also, if the delay before the contraction is to avoid mouse leave by mistake, it's not necessary at all - better animation could perfectly capable of responding on interruption.
Why it should have a contraction animation:
The expand animation is designed, why no contraction animation?
I wanna know if this will be improved in a later version.
I'm using Firefox now because I can't stand this stiff animation, as I really need vertical tab.