ACM: Ubiquity - Crafting a Revolution: "...we know that an average on-screen cursor move takes 3.5 seconds (starting with hands on the keyboard). This may not seem like a large amount of time, but cursor motion is a frequent activity. If you move the cursor a hundred times in the course of an hour then you have spent almost six minutes, roughly 10% of your time, getting nothing productive done. Even seemingly small interface inefficiencies add up.
UBIQUITY: What's your alternative?
AZA [Raskin, Jef Raskin's son]: We have a mechanism called 'Leap.' Leap is an incremental search, meaning that when you want to move the cursor, you find where you want to go, hold down the Leap key, and type what you see. The cursor seems to just appear where you want it to be. Once people sit down and use our system, they never want to leave because Leap is that addictive. When I have to work outside of THE, I find myself reaching for the Leap key all of the time.
UBIQUITY: And so you've shown that this is the fastest way to search text?
AZA: Let me give you a comparison. In the same experiment I mentioned before, it took users an average of 1.5 seconds to move the cursor using Leap, yielding a 43% increase of speed when compared with the mouse. With the same hundred-cursor-moves-in-an-hour scenario, you would spend only two and a half minutes positioning the cursor, wasting only 4% of your time."