There are there are two complimentary factors that contribute to apparent speed.
First, there is raw speed. This is the ability to move in a straight line a certain distance in a certain amount of time.
Second, there is agility. This is the ability to change direction quickly and react effectively to new situations.
From my perspective, agility is the superior attribute, though both are important. To illustrate why, I'll quote Helmuth von Moltke the Elder by making the statement "No plan survives first contact with the enemy". Following this adage, it's easy to see how raw speed can actually become an impediment should you be speedily moving in the wrong direction. This can be further aggravated if you are able to move quickly, but unable to change direction.
Changing gears to software development, many folks confuse agility with speed. They get sold on the idea that software agility will somehow make their development faster. This is really not true and is selling the advantage of agility short. When focusing on agility, you will lose focus on raw speed and a side effect can be that you effectively move slower. What you WILL gain, however, is the ability to move in the appropriate direction at the appropriate time and make course corrections as necessary.