Lately, I have been thinking about speed as the number one factor for software satisfaction. When a piece of software is fast, it makes the user so much happier than if it is just “powerful”.
For example, in the early 90’s I loved XTreeGold. It was wicked fast and could do what I wanted so much faster than any windows software. (It worked in DOS mode). I also loved InfoSelect for exactly the same reason. It was superfast!
This is why Vista users are unhappy. The GUI is just too damn slow. Why is this? It takes me as much time to launch a browser today as it did 10 years ago on my Pentium 100 mhtz.
The point I am making is that speed is a huge differentiating factor for you against your competition. This may mean more hardware for your Web app, or it may mean a bigger database or more robust architecture. Fundamentally, you need to make your software “pop”. When you click something it should work within 1 second.
Interestingly on this subject, WordPress just added a ‘Turbo’ Mode. It uses Google Gears to move alot of the functionality local for the purpose of speed. Speed, speed and more speed.