

Like a lot of things, it works best when you can’t really consciously tell that it’s there.
An animation that’s too quick to really register is fulfilling the brief and making the interface better, without cluttering up the user’s conscious awareness. An animation that wants to slow down enough so that you can really feel that the designer put some work into this interface, and appreciate what genius they are, is no good.
Yes. The random chemicals that go into these drinks do all kinds of weird bullshit. I have had some that more or less put me to sleep, and when I was consistently drinking canned energy stuff my energetic level was pretty much all over the place.
If you need short-term energy to force your body to burn up some resources that ordinarily it would be saving up (and delay some maintenance depending), then drink caffeine. Some of the crash that you’re describing could be aftereffects of that, or it could be some other chemical reaction. Green tea seems like it works pretty clean, coffee is fine in my opinion.
If you need long-term energy, then get consistent exercise, eat enough and a balanced diet, and sleep enough. I know it’s easier said than done, but those are the options that will work and not fuck up your health / energy levels over time.