Speed matters

Greg Linden recounts Marissa Mayer's talk at Web 2.0 showing how even very small decreases in performance have highly measurable impacts on users, and for web businesses on the bottom line.

The change was an increase from 10 to 30 search results, which was expected to produce an increase in user satisfaction, because users had asked for more search results. Instead, there was a completely unexpected and at first inexplicable 20% drop in traffic after the change was implemented. Only after some time did the team discover that the new results page took half a second longer to display, and in further testing they found that every 100 ms delay caused a measurable drop in clicks.

While I am not aware of similar research on desktop apps, I am sure that the same principle applies: speed matters, a lot; and it matters pre-consciously, that is, long before users will mention speed as an issue.