A good article by Tal Mishali on UX MAG about wait time: communicating progress in UI Design.
When an action we perform happens faster than we would expect it to, we may not appreciate the effort put into it. In more extreme cases we may think that if it happened too fast, maybe it didn’t happen at all.
Full article here: http://uxmag.com/articles/let-your-users-wait
I always find interesting to design aspects of software where it is necessary to communicate progress and provide feedback when the action is accomplished. This is a typical application of ‘microinteractions’, where small design details like a well design progress indicator can provide surprise and delight.
Well designed microinteractions can go a long way in making your service stand out from your competitors.