Their performance varies considerable, they are often idle, and then might have an occasional flurry of activity. For example, if their attendance is sporadic, they may have good attendance for a while, and then disappear unpredictably from time to time.
well voracious person is someone who is very hungry or is eating large quantities of food. But it could also mean someone who is very eager to do an activity. Sporadic is somethign very on-off like rain. it could star raining for 10 minutes, stop, and then start again. That would be some sporadic rain.
