Instead of waiting a set amount of time and then checking "current" usage, which is an instant check and can have sudden ups and downs... Check the current usage every 5 sec and keep track of it for a set amount of time. Think of the "load average" in linux: there are three numbers, the avg for 1 minute, avg for 5 minutes, and avg for 15 minutes. Calculate load average for those time periods, make the time periods configurable, and sleep when all 3 are below a certain threshold.
