[Jee Labs] has worked out how long it takes for an Arduino to perform various I/O operations. Predictably, analogRead() takes the longest, followed by analogWrite(). Arduino really falls behind when it comes to digital pin I/O: digitalWrite() takes a whopping fifty times longer than a direct bit write to a port register! This is something to take into consideration when you are looking to do some beefy I/O with an Arduino. Perhaps this I/O performance will be addressed in the future with Arduino 1.0.