Programming a Robot (from a novice)

I've never done robotics before, and I'm pretty sure the robotics guys would say I still haven't.
The biggest problem I had was the delay between steps.
It turns out that I was getting a 200 ms lag in changing the motor.
The key here was to get a better arduino library that didn't wait as long. When it got to 20 ms, it was fine.
Another problem was that the robots differ. Motors have variance and one setting on one robot made the wheel turn faster than on another. We fixed that with a tuning variable for each motor. The sensors seemed quite uniform.
The pi is really quite weak. We can simulat 100,000 neurons in real time on a PC. We managed about 400 on the Pi.