Forget smart watches, I have yet to use a smart phone that doesn't fail the 3-second rule on nearly every task. Often it's 5 seconds of waiting for the phone to catch up between each and every action (each tap, swipe, etc.), so that just loading a website takes a full minute (plus the time actually required download the requisite data). Half the time, if I'm at home, I'll start doing something on my phone and then decide that walking into the other room to do it on my laptop is going to be faster than waiting for the phone.
I've only used Androids. Is it any better in iOS land?
It is much better in iOS land, but only if you have an iPhone which is <2 generations old. I have an old iPhone 4 that's still in great condition but it's completely unusable. The Uber app takes >5 minutes to start up (I timed it). But my new iPhone 6s is lightning fast... As fast as the 4 was when I first got it -_-
If you are using iOS 8 on the iPhone 4, make sure you turn on "reduce motion" and turn on "reduce transparency" in settings > accessibility > increase contrast. That alone made my iPad 2 go from garbage unusable, to, ok.
Transparency and blur effects seem to be the culprit for most slowness on older devices.
I've only used Androids. Is it any better in iOS land?