Perceived performance makes for a great user experience. Tricks where the developers took the time to look at the user interaction. A web example may be here o

Perceived performance makes for a great user experience. Tricks where the developers took the time to look at the user interaction. A web example may be here on news.yc when I upvote a comment, I see it's done instantly even though ajax wizardry in the background does it. Sure is better than doing a whole page refresh. One perceived speed example I absolutely love is on the iPhone. Everything "feels" so snappy and fast when in reality it isn't much better than the competitors. Applications can use an image of their UI - a default view while the device really loads the application in the background and then switches from picture to app when loaded. Combine that with the zooming effects and it FEELS like apps load instantly and makes me FEEL like I love the experience, even though I can't actually interact with the application for up to a second. I think it takes a very good engineer to come up with these little tricks. Perceived performance has real world satisfaction benefits.