> What I dislike the most on modern UI, and maybe absolutely hate, are all those super slow animations.

Slow animations are a way to hide latency, they are essentially loading screens. Apple is really good at it, or at least it was with the early iPhones, and a reason why iPhones felt so smooth compared to their Android counterparts while not being actually faster. For me, it is an impressive technical feat and it took years for Android to catch up (see: "project butter"), and in the end, it was mostly by brute force, i.e. putting ridiculously overpowered hardware in smartphones.

Remove the animations or make them faster (you can do that sometimes), and the lag may become apparent.

Why you have latency to hide in the first place is another problem. There may also be some clueless designers who put slow animations for no good reason, maybe because they are just copying Apple, not understanding why Apple did it in the first place.

There are also some animations that that have utility beyond eye candy in communicating to the user what’s going on, which is particularly important for non-technical individuals.

For example the animation associated with minimizing windows in most desktop environments makes it crystal clear where your window went after you press the minimize button, even for novices. Removing that animation makes the interaction significantly more confusing.

Well, the iPhones were in fact faster. Faster at playing the animations, at least.

I worked on an app in the iPhone 4S and Galaxy S II era and we wanted to use the same trick on both: smoothly animate the view switch between user interaction event and the API response. It worked super smooth on iPhone, and it was jittery as hell on Android. In the end we left the animation on the former, and move the users straight into the loading screen on the latter.

> Slow animations are a way to hide latency, they are essentially loading screens.

Except that most of the time there really isn't any latency to be hidden, the action becomes effectively instant once you remove the animation. Starting a new app (or switching to an app that was evicted from memory) is the main exception and that's quite rare.

> Remove the animations or make them faster (you can do that sometimes), and the lag may become apparent.

This is my number one trick on Android phones. Enable developer options and change the animation speeds from 1x to 0.5x. It makes your old phone feel new.

> Apple is really good at it, or at least it was with the early iPhones, and a reason why iPhones felt so smooth compared to their Android counterparts while not being actually faster.

Is that why iOS animations always feel so slow to me? Modern phone hardware can do things so much faster, but the animations are still utterly sluggish in my opinion. Worse, there's no way to speed them up; even with reduced motion, slow movements are simply translated into just-as-slow fades, which are somehow even more obnoxious.

> Slow animations are a way to hide latency, they are essentially loading screens. Apple is really good at it, or at least it was with the early iPhones, and a reason why iPhones felt so smooth compared to their Android counterparts while not being actually faster.

Now it got flipped. I turned off animations on my Android phone, and it's great. And now every time I have to use iOS (for app development), everything seems to be moving in slow motion.

And you can not turn it off! Apple in their infinite wisdom doesn't provide ways for app developers to disable animated transitions.