Two points: 1) As programmers we're biased to feel like speed is the most important thing because it's very fun and satisfying to optimize. In reality, for act

Two points: 1) As programmers we're biased to feel like speed is the most important thing because it's very fun and satisfying to optimize. In reality, for actual users, it's one of many different axes of value that have to be weighed against each other. In some domains it's critical, in some it matters very little, in most cases it's one important factor among many. 2) There are different types of "speed". Generally anything that's supposed to mimic something physical - basic UI feedback, real-time games/simulations, etc - has a much higher speed requirement than some abstract process. Will the process take long enough that it makes sense to show a loading spinner at all? Then the user probably won't mind waiting a couple extra seconds. Will it take <500ms? then the user will approximate it to "instant", and will notice if there's a bit of "lag". > Phones in 2007 had the same features as the iPhone. The Palm Treo even had a touch screen. The difference was speed. If the original iPhone had taken twice as long as the Treo to load a web page, but the touch screen was still more responsive, people still would have perceived it as being "faster". The extra seconds matter less than shaving off the extra milliseconds.