An adjustable speed control system includes a reader, databases, processors and a conveyor controller. The databases store data concerning conveyor stops and failed attempts by the reader to identify conveyed items. Based on the failed attempts and the conveyor stops, the processors calculate an optimal speed of the conveyor. The controller adjusts the conveyor speed towards the optimal speed to increase the conveyed items successfully identified by the reader. Also disclosed are a corresponding method and computer readable medium on which is stored instructions to, upon execution, adjustably control the conveyor speed.